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NOT MEASUREMENT
SENSITIVE
DOE-HDBK-1109-97 August 1997
CHANGE NOTICE NO. 1 February 2002
___________________ Reaffirmation with Errata July 2002
DOE HANDBOOK RADIOLOGICAL SAFETY TRAINING FOR RADIATION-PRODUCING (X-RAY) DEVICES
U.S. Department of Energy FSC 6910 Washington, D.C. 20585
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
This document has been reproduced from the best available copy. Available to DOE and DOE contractors from ES&H Technical Information Services, U.S. Department of Energy, (800) 473-4375, fax: (301) 903-9823. Available to the public from the U.S. Department of Commerce, Technology Administration, National Technical Information Service, Springfield, VA 22161; (703) 605-6000.
DOE-HDBK-1109-97
iii
Foreword
This Handbook describes a recommended implementation process for additional standardized training as outlined in the DOE Radiological Control Standard (RCS). The Handbook is to assist those individuals within the Department of Energy (DOE), Managing and Operating (M&O) contractors, and Managing and Integrating (M&I) contractors identified as having responsibility for implementing the additional standardized training recommended by the RCS. This training may be given to radiological workers to assist in meeting their job-specific training requirements of 10 CFR 835. This Handbook contains recommended training materials consistent with other DOE additional standardized radiological training material. The training material consists of the following documents:
Program Management Guide - This document contains detailed information on how to use the Handbook material.
Instructor’s Guide - This document contains a lesson plan for instructor use, including notation of key points for inclusion of facility-specific information.
Student’s Guide - This document contains student handout material and also should be augmented by facility-specific information.
This Handbook was produced in Word 2000 and has been formatted for printing on an HP III (or higher) LaserJet printer. Copies of this Handbook may be obtained from either the DOE Radiation Safety Training Home Page Internet site (http://tis.eh.doe.gov/whs/rhmwp/RST/rstmater.htm) or the DOE Technical Standards Program Internet site (http://tis.eh.doe.gov/techstds/). Documents downloaded from the DOE Radiation Safety Training Home Page Internet site may be manipulated using the software noted above (current revision or higher).
DOE-HDBK-1109-97
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DOE-HDBK-1109-97 Part 1 of 3
Radiological Safety Training for Radiation-Producing (X-Ray) Devices
Program Management Guide
Coordinated and Conducted
for Office of Environment, Safety & Health
U. S. Department of Energy
DOE-HDBK-1109-97
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ii
DOE-HDBK-1109-97
iii
Course Developers
Jim Allan Stanford Linear Accelerator Center
Ken Barat Lawrence Berkeley National Laboratory
Rocky Barnum Pacific Northwest National Laboratories
Brooke Buddemeier Lawrence Livermore National Laboratory
Richard Cooke Argonne National Laboratory - East
Ted DeCastro Lawrence Berkeley National Laboratory
William Egbert Lawrence Livermore National Laboratory
Darrel Howe Westinghouse Savannah River Company
David Lee Los Alamos National Laboratory
Kathleen McIntyre Brookhaven National Laboratory
Mike McNaughten Los Alamos National Laboratory
Edward Schultz Sandia National Laboratories
Brian Thomson Sandia National Laboratories
Paula Trinoskey Lawrence Livermore National Laboratory
Susan Vosburg Sandia National Laboratories
Ann Anthony Los Alamos National Laboratory
Course Reviewers
Peter O'Connell U.S. Department of Energy
Randy Sullivan ATL International
Technical Standard Managers U.S. Department of Energy
DOE-HDBK-1109-97
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DOE-HDBK-1109-97
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Table of Contents
Page
Introduction ...................................................................................................................................................1
Purpose and Scope............................................................................................................................1 Management Guide Content .............................................................................................................1 Core Training Goal ...........................................................................................................................1 Organizational Relationships and Reporting Structure........................................................1
Instructional Materials Development .............................................................................................................3
Target Audience ...............................................................................................................................3 Prerequisites......................................................................................................................................3 Training Material ..............................................................................................................................4 Exemptions .......................................................................................................................................4
Training Program Standards and Policies ......................................................................................................5
Qualification of Instructors ...............................................................................................................5 Technical Qualifications ...................................................................................................................5 Instructional Capability and Qualifications.......................................................................................7 Selection of Instructors .....................................................................................................................9 Test Administration ..........................................................................................................................9 Program Records and Administration.............................................................................................12 Training Program Development/Change Requests .........................................................................12 Audit (internal and external)...........................................................................................................12 Evaluating Training Program Effectiveness....................................................................................12 Course-Specific Information ..........................................................................................................14 Purpose ...........................................................................................................................................14 Course Goal ....................................................................................................................................14 Target Audience .............................................................................................................................14 Course Description .........................................................................................................................14 Prerequisites....................................................................................................................................15 Length.............................................................................................................................................15 Test Bank........................................................................................................................................15 Retraining .......................................................................................................................................15 Instructor Qualifications .................................................................................................................16 Materials Checklist .........................................................................................................................17
Bibliography ................................................................................................................................................18
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DOE-HDBK-1109-97
1
Introduction Purpose and Scope This program management guide provides guidance for proper
implementation of additional standardized training as outlined in the
DOE Radiological Control Standard (RCS). The guide is meant to
assist those individuals within the Department of Energy, Managing
and Operating (M&O) contractors, and Managing and Integrating
(M&I) contractors identified as having responsibility for
implementing the additional standardized training recommended by
the RCS. Facilities should determine the applicability of this material
to support existing programs meant to comply with the training
required by 10 CFR 835. Facilities are encouraged to revise these
materials as appropriate.
Management Guide Content The management guide is divided into the following sections:
C Introduction
C Instructional Materials Development
C Training Program Standards and Policies
C Course-Specific Information
Core Training Goal
The goal of the additional standardized training program is to provide
a standardized, baseline knowledge for those individuals completing
the core training. Standardization of the knowledge provides
personnel with the information necessary to perform their assigned
duties at a predetermined level of expertise. Implementing a
standardized training program ensures consistent and appropriate
training of personnel.
Introduction (continued)
DOE-HDBK-1109-97
2
Organizational Relationships
and Reporting Structure
Organizational Relationships
and Reporting Structure
(continued)
The DOE Office of Worker Protection Policy and Programs (EH-52)
is responsible for approving and maintaining the additional
standardized training materials. Continued on Next Page
The establishment of a comprehensive and effective contractor site
radiological safety training program is the responsibility of line
management and their subordinates. The training function can be
performed by a separate training organization, but the responsibility
for quality and effectiveness rests with the line management.
Instructional Materials Development Next
DOE-HDBK-1109-97
3
Instructional Materials Development Target Audience Course instructional materials were developed for specific employees
who are responsible for knowing or using the knowledge or skills for
each course. With this in mind, the participant should never ask the
question, “Why do I need to learn this?” However, this question is
often asked when the participant cannot apply the content of the
program. It is the responsibility of management to select and send
workers to training who need the content of the program. When
workers can benefit from the course, they can be motivated to learn
the content and apply it on their jobs. Care should be taken to read
the course descriptions along with the information about who should
attend. Participants and DOE facilities alike will not benefit from
workers attending training programs unsuitable for their needs.
Prerequisites A background and foundation of knowledge facilitates the trainee in
learning new knowledge or skills. It is much easier to learn new
material if it can be connected or associated to what was previously
learned or experienced. Curriculum developers who have been
involved in preparing instructional materials for the core training
know this and have established what is referred to as “prerequisites”
for each course.
Certain competencies or experiences of participants were also
identified as necessary prior to participants attending a course.
Without these competencies or experiences, the participants would be
at a great disadvantage and could be easily discouraged and possibly
fail the course. It is not fair to the other participants, the unprepared
participant, and the instructor to have this misunderstanding.
Continued on Next Page
Instructional Materials Development (continued)
DOE-HDBK-1109-97
4
Training Material
Training materials for this training program consist of a program
management guide, an instructor’s guide, and a student’s guide.
This material is designed to be supplemented with facility-specific
information.
Supplemental material and training aids may be developed to address
facility-specific radiological concerns and to suit individual training
styles. References are cited in each lesson plan and may be used as a
resource in preparing facility-specific information and training aids.
Each site is responsible for establishing a method to differentiate the
facility-specific information from the standardized lesson plan
material. When additional or facility-specific information is added to
the text of the core lesson plan material, a method should be used to
differentiate facility information from standardized material.
Exemptions Qualified personnel can be exempted from training if they have
satisfactorily completed training programs (i.e., facility, college or
university, military, or vendor programs) comparable in instructional
objectives, content, and performance criteria. Documentation of the
applicable and exempted portions of training should be maintained.
Training Program Standards and Policies Next
DOE-HDBK-1109-97
5
Training Program Standards and Policies Qualification of Instructors The technical instructor plays a key role in the safe and efficient
operation of DOE facilities. Workers must be well qualified and
have a thorough understanding of the facility's operation, such as use
and maintenance of radiation-producing devices. Workers must know
how to correctly perform their duties and why they are doing them.
They must know how their actions influence other workers’
responsibilities. Because workers' actions are so critical to their own
safety and the safety of others, their trainers must be of the highest
caliber. The technical instructor must understand thoroughly all
aspects of the subjects being taught and the relationship of the subject
content to the total facility. Additionally, the instructor must have the
skills and knowledge to employ the instructional methods and
techniques that will enhance learning and successful job
performance. While the required technical and instructional
qualifications are listed separately, it is the combination of these two
factors that produces a qualified technical instructor.
The qualifications are based on the best industry practices that
employ performance-based instruction and quality assurance. These
qualifications are not intended to be restrictive, but to help ensure that
workers receive the highest quality training possible. This is only
possible when technical instructors possess the technical competence
and instructional skills to perform assigned instructional duties in a
manner that promotes safe and reliable DOE facility operations.
Technical Qualifications Instructors must possess technical competence (theoretical and
practical knowledge along with work experience) in the subject areas
in which they conduct training. The foundation for
Continued on Next Page
Training Program Standards and Policies (continued)
DOE-HDBK-1109-97
6
Technical Qualifications
(continued)
determining the instructor's technical qualifications is based on two
factors:
C the trainees being instructed and
C the subject being presented.
The following is an example of a target audience, subject to be
taught, and instructor technical qualifications.
TARGET AUDIENCE
SUBJECT BEING
TAUGHT
INSTRUCTOR QUALIFICATIONS
Radiation-Producing
Device (RPD) Operators
and staff associated with
operation, maintenance, or
radiation safety of RPDs.
Radiological Safety
training for
Radiation-
Producing (X-ray)
Devices.
Demonstrated knowledge and skills in
radiation protection, above the level to be
achieved by the trainees, as evidenced by
previous training/education and through
job performance.
Methods for verifying the appropriate level of technical competence
may include review of prior training and education, observation, and
evaluation of recent related job performance, and oral or written
examination. Other factors that may be appropriate for consideration
include DOE, NRC, or other government license or
certification; vendor or facility certification; and most importantly,
job experience. To maintain technical competence, a technical
instructor should continue to perform satisfactorily on the job and
participate in continuing technical training.
Continued on Next Page
Training Program Standards and Policies (continued)
DOE-HDBK-1109-97
7
Instructional
Capability and Qualifications
Qualifications of instructional capability should be based on
demonstrated performance of the instructional tasks for the specific
course requirements and the instructor's position. Successful
completion of instructor training and education programs, as well as
an evaluation of on-the-job performance, is necessary for verification
of instructional capability. Instructional capability qualification
should be granted as the successful completion of an approved
professional development program for training instructors. The
program should contain theory and practice of instructional skills and
techniques; adult learning; and planning, conducting, and evaluating
classroom, simulator, laboratory, and on-the-job training activities.
Illustrated talks, demonstrations, discussions, role playing, case
studies, coaching, and individual projects and presentations should be
used as the principal instructional methods for presenting the
instructional training program. Each instructional method should
incorporate the applicable performance-based principles and
practices. Every effort should be made to apply the content to actual
on-the-job experience or to simulate the content in the classroom/
laboratory. The appropriate methodology required to present the
instructional content will indicate a required level of instructional
qualification and skill.
Current instructors' training, education, and job performance should
be reviewed to determine their training needs for particular courses.
Based on this review, management may provide exemptions based on
demonstrated proficiency in performing technical instructor's tasks.
Continued on Next Page
Instructional Capability and
Training Program Standards and Policies (continued)
DOE-HDBK-1109-97
8
Qualifications (continued)
Through training or experience, technical instructors should be able
to*:
C Review instructional materials and modify to fully meet the
needs of the training group.
C Arrange the training facility (classroom/laboratory or other
instructional setting) to meet the requirements for the training
sessions.
C Effectively communicate, verbally and non-verbally, lessons to
enhance learning.
C Invoke student interaction through questions and student
activity.
C Respond to students’ questions.
C Provide positive feedback to students.
C Use appropriate instructional materials and visual aids to meet
the lesson objectives.
C Administer performance and written tests.
C Ensure evaluation materials and class rosters are maintained and
forwarded to the appropriate administrative personnel.
C Evaluate training program effectiveness.
Continued on Next Page
Training Program Standards and Policies (continued)
DOE-HDBK-1109-97
9
Instructional Capability and
Qualifications (continued)
C Modify training materials based on evaluation of training
program.
*Stein, F. Instructor Competencies: The Standards. International
Board of Standards for Training, Performance and Instruction; 1992.
Selection of Instructors Selection of instructors should be based on the technical and
instructional qualifications specified in the Course-Specific
Information section of this guide. In addition to technical and
instructional qualifications, oral and written communication skills and
interpersonal skills should be included in the process of selecting and
approving instructors.
Since selection of instructors is an important task, those who share in
the responsibility for ensuring program effectiveness should:
C interview possible instructors to ensure they understand the
importance of the roles and responsibilities of technical
instructors and are willing to accept and fulfill their
responsibilities in a professional manner.
C maintain records of previous training, education, and work
experience.
Procedures for program evaluation will include documentation of
providing qualified instructors for generic and facility-specific
training programs.
Test Administration
A test bank of questions for each course that has an exam should be
developed and content validated. As the test banks are used,
Continued on Next Page
Training Program Standards and Policies (continued)
DOE-HDBK-1109-97
10
Test Administration
(continued)
statistical validation of the test bank should be performed to fully
refine the questions and make the tests as effective as possible. The
questions contained in the test bank are linked directly to the
objectives for each course. In this way, trainee weaknesses can be
readily identified and remedial procedures can be put into place. The
test outcomes can also be used to document competence and the
acquisition of knowledge.
The test banks should also be used by the instructors to identify
possible weaknesses in the instruction. If numerous trainees fail to
correctly answer a valid set of questions for an objective, the
instruction for that objective needs to be reviewed for deficiencies.
Written examinations may be used to demonstrate satisfactory
completion of theoretical classroom instruction. The following are
some recommended minimal requirements for the test banks and
tests:
C Tests are randomly generated from the test bank.
C Test items represent all objectives in the course.
C All test bank items are content-validated by a subject matter
expert.
C Test banks are secured and not released either before or after the
test is administered.
C Trainees should receive feedback on their test performance.
Continued on Next Page
Training Program Standards and Policies (continued)
DOE-HDBK-1109-97
11
Test Administration
(continued)
C For the first administrations of tests, a minimum of 80% should
be required for a passing score. As statistical analyses of test
results are performed, a more accurate percentage for a passing
score should be identified.
Test administration is critical in accurately assessing the trainee's
acquisition of knowledge being tested. Generally, the following rules
should be followed:
C Tests should be announced at the beginning of the training
sessions.
C Instructors should continuously monitor trainees during
examinations.
C All tests and answers should be collected at the conclusion of
each test.
C No notes can be made by trainees concerning the test items.
C No talking (aside from questions) should be allowed.
C Answers to questions during a test should be provided, but
answers to test items should not be or alluded to or otherwise
provided.
C Where possible, multiple versions of each test should be
produced from the test bank for each test administration.
Continued on Next Page
Training Program Standards and Policies (continued)
DOE-HDBK-1109-97
12
Test Administration
(continued)
C After test completion, trainees may turn in their materials and
leave the room while other trainees complete their tests.
C Trainee scores on the tests should be held as confidential.
Program Records and
Administration
Training records and documentation shall meet the requirements of
10 CFR 835.704.
Training Program
Development/Change
Requests
All requests for program changes and revisions should use the form
“Document Improvement Proposal” provided at the end of this
document.
Audit (internal and external) Internal verification of training effectiveness should be accomplished
through senior instructor or supervisor observation of practical
applications and discussions of course material. All results should be
documented and maintained by the organization responsible for
Radiological Control training.
The additional standardized training program materials and processes
should be evaluated on a periodic basis by DOE-HQ. The evaluation
should include a comparison of program elements with applicable
industry standards and requirements.
Evaluating Training Program
Effectiveness
Verification of the effectiveness of Radiological Control training
should be accomplished per DOE-HDBK-1131-98, “General
Employee Radiological Training,” and DOE-HDBK-1130-98,
“Radiological Worker Training.” In addition, DOE/EH
Continued on Next Page
Training Program Standards and Policies (continued)
DOE-HDBK-1109-97
13
Evaluating Training Program
Effectiveness (continued)
has issued guidelines for evaluating the effectiveness of radiological
training through the DOE Operations Offices and DOE Field Offices.
For additional guidance, refer to DOE-STD-1070-94, “Guide for
Evaluation of Nuclear Facility Training Programs.”
DOE-HDBK-1109-97
14
Course-Specific Information Purpose This section of the program management guide is to assist those
individuals assigned responsibility for implementing the Radiological
Safety Training for Radiation-Producing (X-Ray) Devices.
Course Goal Upon completion of this training, the student will have a basic
understanding of the principles of RPD operation, safety
requirements, and classification of various types of radiation-
producing devices.
Target Audience Individuals who have assigned duties as RPD operators; also staff
associated with operation, maintenance, and radiation safety of RPDs.
Course Description This course illustrates and reinforces the skills and knowledge needed
for RPD operators in the basics of safe operation of RPDs.
The purpose of this lesson is to provide information on each of the
primary RPDs and discuss the applicable rules governing the use of
these devices. Utilizing the requirements and recommendations from
ANSI N43.2 and ANSI N43.3, this course will establish guidelines
for the proper use of common types of installations that:
• Use X-ray diffraction and fluorescence analysis equipment
(analytical) and
• Use X-ray machines up to 10 million electron volts (MeV) for
non-medical purposes (industrial).
Course Description The primary emphasis of these standards and this class is to keep
Course-Specific Information (continued)
DOE-HDBK-1109-97
15
(continued) worker exposure to ionizing radiation at levels that are as low as
reasonably achievable (ALARA) and to ensure that no worker
receives greater than the maximum permissible dose equivalent.
This course is designed to be consistent with Article 655 of the DOE
Radiological Control Standard for individuals who have assigned
RPD duties.
Prerequisites This training material is designed to augment the DOE Radiological
Worker core training. As a refresher, this course includes
Radiological Worker training material, as applicable to RPD
operators, but is not intended to replace Radiological Worker
training. The first module of this course may be issued as a self-
study. It is a general overview of Radiological Worker topics. The
presentation may be adjusted accordingly.
The facility training program should determine the appropriate
prerequisites. However, it is recommended that students complete
Radiological Worker training and High/Very High Radiation Area
training or the equivalent, prior to taking this course.
Length 4-8 hours (depending on facility-specific information)
Test Bank On a site-by-site basis.
Retraining Retraining is not required for this course unless it is used to meet
10 CFR 835 training requirements. In that case, retraining every two
years is required. Since some of the content is determined on a
facility-specific basis, retraining should also be provided as facility-
specific information changes.
Continued Next Page Instructor Qualifications Instructors of this course have a major role in making it successful
and meeting the specified objectives. Instructors must have related
Course-Specific Information (continued)
DOE-HDBK-1109-97
16
experience and be technically competent. In this course it is
imperative that the instructor have the background and experience of
working with RPDs. Instructors must be able to relate their own
work experience to the workers assigned duties as RPD operators.
Instructors must be able to answer specific questions and use a variety
of instructional material to meet the objectives.
Education: Minimum of B.S. degree in Health Physics or related
discipline is preferred.
Certification: Certification by American Board of Health Physics
(ABHP) or National Registry of Radiation Protection
Technologists (NRRPT) is preferred.
Experience:
At least five years of applied radiological protection experience in an
operating radiological facility including experience as a RPD operator
is preferred. The areas of experience should include one or more of
the following:
C Analytical (fluorescence or diffraction) X-ray devices
C Medical (diagnostic or therapeutic) X-ray devices
C Industrial radiography
C Electron or low-energy accelerators.
C Knowledge of best nuclear industry practices pertaining to
radiological protection with respect to RPDs.
Continued on Next Page
Through training or experience, technical instructors should be able
to effectively communicate, verbally and non-verbally, lessons to
enhance learning.
Course-Specific Information (continued)
DOE-HDBK-1109-97
17
Materials Checklist The following checklist should be used to ensure all training
materials are available. All materials are provided in Word 2000
format.
C Program Management Guide.
C Instructor's Guide.
C Student's Guide.
Bibliography Next
DOE-HDBK-1109-97
18
Bibliography: DOE standards, handbooks, and technical standards lists (TSLs). The
following DOE standards, handbooks, and TSLs form a part of this
document to the extent specified herein.
U.S. Department of Energy, Guide to Good Practices for Training and
Qualification of Instructors, DOE-NE-STD-1001-91, Washington, D.C., 1991.
U.S. Department of Energy, Radiological Control Standard, DOE-STD-1098-99,
Washington, D.C., 1999.
U.S. Department of Energy, Radiation Generating Devices Guide,
Implementation Guide for Use with Title 10, Code of Federal Regulations, Part
835, Occupational Radiation Protection, Washington, D.C., 1999.
U.S. Department of Energy, Radiation Safety Training Guide, Implementation
Guide for Use with Title 10, Code of Federal Regulations, Part 835, Occupational
Radiation Protection, Washington, D.C., 1999.
U.S. Department of Energy, Title 10, Code of Federal Regulations, Part 835,
Occupational Radiation Protection, Washington, D.C., 1998.
Other government documents, drawings, and publications. The following
government documents, drawings, and publications form a part of this
document to the extent specified herein. Unless otherwise indicated, the
issues of these documents are those cited in the contracting document.
U.S. Nuclear Regulatory Commission, Title 10, Code of Federal Regulations, Part
34, Subpart 31, Licenses for Radiography and Radiation Safety Requirements for
Radiographic Operations, Section 34.31 “Training,” Washington, D.C., 1979.
DOE-HDBK-1109-97
Bibliography (continued)
19
Non-government documents.
American National Standards Institute, Radiation Safety for X-Ray Diffraction
and Fluorescence Analysis Equipment, ANSI Standard N43.2, American National
Standards Institute, New York, NY, 1977 (reaffirmed 1989).
American National Standards Institute, American National Standard for General
Radiation Safety Installations Using Non-Medical X-Ray and Sealed Gamma-Ray
Sources, Energies up to 10 MEV, ANSI Standard N43.3, American National
Standards Institute, New York, NY, 1993.
Cooper, L., An Introduction to the Meaning and Structure of Physics, Harper &
Row, Publishers, New York, NY, 1968.
Shleien, B., The Health Physics and Radiological Health Handbook, Revised
Edition, Scinta Inc., Silver Spring, MD, 1992.
National Council on Radiation Protection and Measurements, Radiation Safety
Training Criteria for Industrial Radiography, NCRP Report, No. 61,
Washington, D.C., 1978.
DOE-HDBK-1109-97
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DOE-HDBK-1109-97 Part 2 of 3
Radiological Safety Training for Radiation-Producing (X-Ray) Devices
Instructor’s Guide
Coordinated and Conducted for
Office of Environment, Safety & Health U.S. Department of Energy
DOE-HDBK-1109-97
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DOE-HDBK-1109-97
Radiological Safety Training for Radiation-Producing (X-Ray) Devices Instructor's Guide
iii
Course Developers
Jim Allan Stanford Linear Accelerator Center
Ken Barat Lawrence Berkeley National Laboratory
Rocky Barnum Pacific Northwest National Laboratories
Brooke Buddemeier Lawrence Livermore National Laboratory
Richard Cooke Argonne National Laboratory - East
Ted DeCastro Lawrence Berkeley National Laboratory
William Egbert Lawrence Livermore National Laboratory
Darrel Howe Westinghouse Savannah River Company
David Lee Los Alamos National Laboratory
Kathleen McIntyre Brookhaven National Laboratory
Mike McNaughten Los Alamos National Laboratory
Edward Schultz Sandia National Laboratories
Brian Thomson Sandia National Laboratories
Paula Trinoskey Lawrence Livermore National Laboratory
Susan Vosburg Sandia National Laboratories
Ann Anthony Los Alamos National Laboratory
Course Reviewers
Peter O'Connell U.S. Department of Energy
Randy Sullivan ATL International
Technical Standard Managers U.S. Department of Energy
DOE-HDBK-1109-97
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v
Table of Contents
Page
DEPARTMENT OF ENERGY - COURSE PLAN.......................................................................................1 Standardized Core Course Material ..............................................................................................................1
Course Goal ......................................................................................................................................1 Target Audience ...............................................................................................................................1 Description........................................................................................................................................1 Length...............................................................................................................................................2 Terminal Objective ...........................................................................................................................2 Enabling Objectives..........................................................................................................................2 Regulations .......................................................................................................................................3 Equipment Needs..............................................................................................................................4 Student Materials ..............................................................................................................................4 ANSI.................................................................................................................................................5
LESSON SUMMARY ..................................................................................................................................6
Introduction .....................................................................................................................................6 Course Goal ......................................................................................................................................6 Course Content .................................................................................................................................6
I. MODULE 101 - RADIATION PROTECTION PRINCIPLES........................................................7
A. OBJECTIVES ......................................................................................................................7 B. ATOMS................................................................................................................................8 C. IONIZATION .....................................................................................................................8 D. RADIATION........................................................................................................................8 E. UNITS..................................................................................................................................9 F. BACKGROUND RADIATION.........................................................................................10 G. DOSE LIMITS ...................................................................................................................11 H. CAUSES OF ACCIDENTAL EXPOSURES (KEY ITEM)..............................................13 I. ALARA..............................................................................................................................14 J. REDUCING EXTERNAL DOSE (KEY ITEM) ...............................................................14
II. MODULE 102 - PRODUCTION OF X-RAYS .............................................................................16
A. OBJECTIVES ....................................................................................................................16 B. ELECTROMAGNETIC RADIATION..............................................................................17 C. X-RAY PRODUCTION.....................................................................................................19 D. EFFECT OF VOLTAGE AND CURRENT ON PHOTON ENERGY AND POWER.....21 E. INTERACTION WITH MATTER ....................................................................................23
III. MODULE 103 - BIOLOGICAL EFFECTS...................................................................................28
A. OBJECTIVES ....................................................................................................................28 B. EARLY HISTORY OF X-RAYS ......................................................................................29 C. BIOLOGICAL EFFECTS OF IONIZATION....................................................................31 D. FACTORS THAT DETERMINE BIOLOGICAL EFFECTS ...........................................31 E. SOMATIC EFFECTS ........................................................................................................35 F. HERITABLE EFFECTS...................................................................................................41
DOE-HDBK-1109-97
Radiological Safety Training for Radiation-Producing (X-Ray) Devices Instructor's Guide
vi
IV. MODULE 104 - RADIATION DETECTION ...............................................................................43 A. OBJECTIVES ....................................................................................................................43 B. RADIATION SURVEYS...................................................................................................43 C. X-RAY DETECTION INSTRUMENTS ...........................................................................43 D. PERSONNEL-MONITORING DEVICES ........................................................................45
V. MODULE 105 - PROTECTIVE MEASURES ..............................................................................48
A. OBJECTIVES ....................................................................................................................48 B. RADIOLOGICAL CONTROLS........................................................................................49 C. RADIOLOGICAL POSTINGS..........................................................................................50 D. INTERLOCKS...................................................................................................................54 E. SHIELDING.......................................................................................................................55 F. WARNING DEVICES.......................................................................................................58 G. WORK DOCUMENTS......................................................................................................59
VI. MODULE 106 - X-RAY GENERATING DEVICES....................................................................63
A. OBJECTIVES ....................................................................................................................63 B. INCIDENTAL AND INTENTIONAL DEVICES.............................................................64 C. INCIDENTAL X-RAY DEVICES ....................................................................................65 D. INTENTIONAL ANALYTICAL X-RAY DEVICES .......................................................66 E. INTENTIONAL INDUSTRIAL X-RAY DEVICES .........................................................70 F. SUMMARY OF X-RAY DEVICES..................................................................................74
VII. MODULE 107 - RESPONSIBILITIES FOR X-RAY SAFETY....................................................76
A. OBJECTIVES ....................................................................................................................76 B. RESPONSIBILITIES.........................................................................................................77
GLOSSARY................................................................................................................................................82
DOE-HDBK-1109-97
Radiological Safety Training for Radiation-Producing (X-Ray) Devices Instructor's Guide
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DEPARTMENT OF ENERGY - COURSE PLAN
Standardized Core Course Material Course Goal Upon completion of this training, the student will have a basic
understanding of the principles of radiation-producing device
(RPD) operation, safety requirements, and classification of various
types of radiation-producing devices.
Other hazards associated with the use of some X-ray machines,
such as electrical, mechanical, laser light, and explosives, are not
addressed in this course because they are specific to particular
machines and procedures. Neither does this course address
operating procedures for specific installations. The participants
will receive training on the specific operating procedures at the
participants’ work site.
Target Audience Individuals who have assigned duties as RPD operators. Also staff
associated with operation, maintenance, and radiation safety of
RPDs.
Description This course illustrates and reinforces the skills and knowledge
needed for RPD operators in the basics of safe operation of RPDs.
The purpose of this lesson is to provide information on each of the
primary RPDs and discuss the applicable rules governing the use of
these devices. Utilizing the requirements and recommendations
from ANSI N43.2 and ANSI N43.3, this course will establish
guidelines for the proper use of common types of installations that
use:
• X-ray diffraction and fluorescence analysis equipment
(analytical) and
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• X-ray machines with energies up to 10 million electron
volts (MeV) for non-medical purposes (industrial).
The primary emphasis of these standards and this course is to keep
worker exposure to ionizing radiation at levels that are as low as
reasonably achievable (ALARA) and to ensure that no individual
receives greater than the maximum permissible dose equivalent.
This course is designed to be consistent with Article 655 of the
DOE Radiological Control Standard for individuals who have
assigned RPD duties.
Length 4 - 8 hours (depending on site-specific information).
Terminal Objective
Demonstrate a basic understanding of :
• General radiation protection principles for safe operation of
X-ray devices.
Enabling Objectives When the participants have completed this course, the participants
will be able to:
EO1 Describe ionizing radiation.
EO2 Describe what X-rays are, how they are generated, and how
they interact with matter.
EO3 Describe the biological effects of X-rays.
EO4 Identify and describe radiation-monitoring instruments and
personnel-monitoring devices appropriate for detecting
X-rays.
EO5 Demonstrate a familiarity with DOE dose limits, facility-
specific administrative controls, ALARA, and the major
methods for controlling and minimizing external exposure.
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EO6 Identify and describe protective measures that restrict or
control access to X-ray areas and devices, and warn of X-ray
hazards; and be able to identify and describe work documents
that provide specific procedures to ensure safe operation of
X-ray devices.
EO7 Identify and describe the categories of X-ray-producing
devices.
EO8 Explain who is responsible for implementing X-ray safety
policies and procedures and describe their specific
responsibilities.
EO9 Identify causes of accidental exposures.
Regulations The prime compliance document for occupational radiation
protection at Department of Energy (DOE) sites is the Code of
Federal Regulations, 10 CFR 835, “Occupational Radiation
Protection”. The DOE Radiological Control Standard provides
detailed guidance on good practices acceptable to the Department
in the area of radiological control.
The American National Standards Institute (ANSI) details safety
guidelines for X-ray devices in two standards, one on analytical
(X-ray diffraction and fluorescence) X-ray equipment and another
on industrial (nonmedical) X-ray installations (ANSI N43.2
{R1989}, Radiation Safety for X-Ray Diffraction and
Fluorescence Analysis Equipment and ANSI N43.3 [1993],
American National Standard for General Radiation
SafetyCInstallations Using Non-Medical X-ray and Sealed
Gamma-Ray Sources, Energies up to 10 MeV). Guidance for X-ray
training is also provided by the Nuclear Regulatory Commission in
10 CFR 19.12 and 10 CFR 34.31.
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(Add information on facility-specific requirements documents as
applicable.)
Most of the information presented in this course is based on the
radiation safety guidelines on X-ray devices contained in ANSI
N43.2, which outlines the safety requirements for X-ray diffraction
and fluorescence equipment, and N43.3, which outlines the safety
requirements for the design, installation, and operation of
industrial (nonanalytical) X-ray installations.
Equipment Needs • Overhead projector
• Screen
• Flip chart
• Markers
• Facility-specific RPD
Student Materials
Student's Guide.
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ANSI The main objectives of ANSI N43.2 and ANSI N43.3 are to keep
worker exposure to ionizing radiation at levels below the maximum
permissible dose equivalent and that are as low as reasonably
achievable (ALARA). These objectives may be achieved through
the following methods:
• Use of emergency controls.
• Using firm administrative controls.
• Using work control documents such as standard operating
procedures (SOPs) and radiological work permits (RWPs).
• Maintaining equipment appropriately.
• Employing a comprehensive maintenance and surveillance
program.
• Using adequate shielding.
• Maximizing distance from the source.
Lesson Summary Next
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LESSON SUMMARY
Introduction
Welcome students to the course.
Introduce self to the participants and establish rapport.
Define logistics:
C Safety briefings - exits.
C Restrooms.
C Hours.
C Breaks.
C Sign-in sheets.
C Test - accountability.
C End-of-course evaluation.
Course Goal
Upon completion of this unit, the participants will understand basic radiation protection principles essential to
the safe operation of X-ray devices.
State Enabling Objectives.
Course Content
Briefly review the content of the course, noting that there is a logical sequence (“flow”), and that as the
instructor presents the material, the participants will relate the material covered to the circumstances that they
can expect to find in the facility workplace and procedures. (The instructor should insert facility-specific
information.)
Lesson Plan and Instructor's Notes Next
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I. MODULE 101 - RADIATION PROTECTION
PRINCIPLES
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the participants
should understand basic radiation protection
principles essential to the safe operation of X-ray
devices.
ii. Objectives.
Following self-study and/or classroom review, the
participants will be able to:
1. Define ionizing radiation.
2. Identify sources of natural and manmade
background radiation.
3. Define the DOE dose limits and facility-
specific administrative control levels.
4. Describe the ALARA principle.
5. List the three major methods by which
external exposure is reduced.
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B. ATOMS
The atom, the basic unit of matter, is made up of three
primary particles: protons, neutrons, and electrons.
Protons and neutrons are found in the nucleus of the
atom; electrons are found orbiting the nucleus. Protons
have a positive charge; neutrons are neutral; electrons
have a negative charge. The configuration of electron
shells and the number of electrons in the shells
determine the chemical properties of atoms.
Objective 1
C. IONIZATION
An atom usually has a number of electrons equal to the
number of protons in its nucleus so that the atom is
electrically neutral. A charged atom, called an ion, can
have a positive or negative charge. Free electrons also
are called ions. An ion is formed when ionizing
radiation interacts with an orbiting electron and causes it
to be ejected from its orbit, a process called ionization.
This leaves a positively charged atom (or molecule) and
a free electron.
D. RADIATION
Radiation as used here means alpha particles, beta
particles, gamma rays, X-rays, neutrons, high-speed
electrons, high-speed protons, and other particles
capable of producing ions. Radiation with enough
energy to cause ionization is referred to as ionizing
radiation. Radiation that lacks the energy to cause
ionization is referred to as non-ionizing radiation.
Objective 1
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Examples of non-ionizing radiation include radio waves,
microwaves, and visible light.
For radiation-protection purposes, ionization is
important because it affects chemical and biological
processes and allows the detection of radiation.
For most radiation-protection situations, ionizing
radiation takes the form of alpha, beta, and neutron
particles, and gamma and X-ray photons.
X-rays and gamma rays are a form of electromagnetic
radiation. X-rays differ from gamma rays in their point
of origin. Gamma rays originate from within the atomic
nucleus, whereas X-rays originate from the electrons
outside the nucleus and from free electrons decelerating
in the vicinity of atoms (i.e., bremsstrahlung). Module
102 discusses how X-rays are produced.
E. UNITS
C Roentgen (R), a measure of radiation exposure, is
defined by ionization in air.
C Rad, a measure of the energy absorbed per unit
mass.
It is defined for any absorbing material.
C Rem, a unit of dose equivalent, which is the energy
absorbed per unit mass times the applicable quality
factor and other modifying factors.
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For X-rays, it may be assumed that 1 R = 1 rad = 1 rem
= 1000 mrem.
F. BACKGROUND RADIATION
Background radiation, to which everyone is exposed,
comes from both natural and manmade sources.
Natural background radiation can be categorized as
cosmic and terrestrial. Radon is the major contributor
to terrestrial background. The most common sources of
manmade background radiation are medical procedures
and consumer products.
The average background dose to the general population
from both natural and manmade sources is about 350
mrem per year to the whole body. Naturally occurring
sources contribute an average of 200 mrem per year
from radon daughters, about 40 mrem per year from
internal emitters such as potassium-40, about 30 mrem
per year from cosmic and cosmogenic sources, and
about 30 mrem per year from terrestrial sources such as
naturally occurring uranium and thorium. Manmade
sources contribute an average of about 50 mrem per year
to the whole body from medical procedures such as
chest X-rays.
The deep dose equivalent from a chest X-ray is 5 - 10
mrem, a dental X-ray is 50 - 300 mrem, and
mammography is 0.5 - 2 rem.
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G. DOSE LIMITS
Limits on occupational doses are based on data on the
biological effects of ionizing radiation. The International
Commission on Radiological Protection and the
National Council on Radiation Protection and
Measurements publish guidance for setting radiation
protection standards. The DOE, Nuclear Regulatory
Commission, and Environmental Protection Agency set
regulatory requirements related to radiation protection.
These limits are set to minimize the likelihood of
biological effects.
Objective 5
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The following table lists both DOE dose limits and
administrative control levels.
Refer to:
10 CFR 835.202-208
DOE Dose Limits and Facility-Specific Administrative Control Levels
DOE
Dose Limits
Facility-Specific
Administrative Control Levels
whole body Total Effective Dose Equivalent
5 rem/year
insert facility-specific value
extremity
50 rem/year
insert facility-specific value
skin
50 rem/year
insert facility-specific value
internal organ committed dose equivalent
50 rem/year
insert facility-specific value
lens of the eye
15 rem/year
insert facility-specific value
embryo/fetus
0.5 rem/term
of pregnancy (for the embryo/fetus of workers who declare pregnancy)
insert facility-specific value
minors and public
0.1 rem/year
insert facility-specific value
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DOE facilities are designed and operated to reduce personnel
dose equivalents as far below the occupational limits as
reasonably achievable. The dose equivalent received by DOE
X-ray workers is typically between 0 and 100 mrem per year
above the natural background.
H. CAUSES OF ACCIDENTAL EXPOSURES (KEY ITEM)
Although most X-ray workers do not receive radiation doses
near the regulatory limit, it is important to recognize that X-ray
device-related accidents have occurred when proper
procedures have not been followed. Failure to follow proper
procedures has been the result of:
• Rushing to complete a job.
• Boredom.
• Fatigue.
• Illness.
• Personal problems.
• Lack of communication.
• Complacency.
Every year there are numerous X-ray incidents nationwide. Of
these, about one third result in injury to a person. The incident
rate at DOE laboratories is much lower than the national
average.
Objective 9
Discuss facility-specific
incidents.
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I. ALARA
Because the effects of chronic doses of low levels of
ionizing radiation are not precisely known, we assume
there is some risk for any dose. The ALARA principle
is to keep radiation dose as low as reasonably
achievable, considering economic and social constraints.
Objective 5
The goal of an ALARA Program is to keep radiation
dose as far below the occupational dose limits and
administrative control levels as is reasonably achievable.
The success of an ALARA Program is directly linked to
a clear understanding and following of the policies and
procedures for the protection of workers. Keeping
radiation dose ALARA is the responsibility of all
workers, management, and the radiation-protection
organization.
J. REDUCING EXTERNAL DOSE (KEY ITEM)
Three basic ways to reduce external doses are to
• Minimize time.
• Maximize distance.
• Use shielding.
Objective 5
Discuss facility-specific methods
to reduce external dose.
Minimize time near a source of radiation by planning
ahead. Increase distance by moving away from the
source of radiation whenever possible. The dose from
X-ray sources is inversely proportional to the square of
the distance. This is called the inverse square law, that
is, when the distance is doubled, the dose is
reduced to one-fourth of the original value. Proper
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facility design uses the amount and type of shielding
appropriate for the radiation hazard. Lead, concrete,
and steel are effective in shielding against X-rays.
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II. MODULE 102 - PRODUCTION OF X-RAYS
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the participants
should understand what X-rays are and how they are
produced so that the participants will be able to
work around them safely.
ii. Objectives.
Following self-study and/or classroom review, the
participants will be able to:
1. Define the types of electromagnetic radiation.
2. Describe the difference between X-rays and
gamma rays.
3. Identify how X-rays are produced.
4. Define bremsstrahlung and characteristic
X-rays.
5. Describe how X-ray tube voltage and current
affect photon energy and power.
6. Explain how X-rays interact with matter.
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7. Identify how energy relates to radiation dose.
8. Discuss the effects of voltage, current, and
filtration on X-rays.
B. ELECTROMAGNETIC RADIATION
i. Types of Electromagnetic Radiation.
X-rays are a type of electromagnetic radiation.
Other types of electromagnetic radiation are radio
waves, microwaves, infrared, visible light,
ultraviolet, and gamma rays. The types of radiation
are distinguished by the amount of energy carried by
the individual photons.
All electromagnetic radiation consists of photons,
which are individual packets of energy. For
example, a household light bulb emits about 1021
photons of light (non-ionizing radiation) per second.
The energy carried by individual photons, which is
measured in electron volts (eV), is related to the
frequency of the radiation. Different types of
electromagnetic radiation and their typical photon
energies are listed in the following table.
Objective 2
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Electromagnetic Radiation
Type
Typical Photon Energy
Typical Wavelengths
radio wave
1 ueV
1 m
microwave
1 meV
1 mm (10-3m)
infrared
1 eV
1 um (10-6m)
red light
2 eV
6000 Angstrom (10-10m)
violet light
3 eV
4000 Angstrom
ultraviolet
4 eV
3000 Angstrom
X-ray
100 keV
0.1 Angstrom
gamma ray
1 MeV
0.01 Angstrom
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ii. X-Rays and Gamma Rays.
X-rays and gamma rays both ionize atoms. The
energy required for ionization varies with material
(e.g., 34 eV in air, 25 eV in tissue) but is generally
in the range of several eV. A 100 keV X-ray can
potentially create thousands of ions.
Objective 2
As discussed in Module 101, the distinction
between X-rays and gamma rays is their origin, or
method of production. Gamma rays originate from
within the nucleus; X-rays originate from atomic
electrons and from free electrons decelerating in the
vicinity of atoms (i.e., bremsstrahlung).
In addition, gamma photons often have more energy
than X-ray photons. For example, diagnostic X-rays
are about 40 keV, whereas gammas from cobalt-60
are over 1 MeV. However, there are many
exceptions. For example, gammas from technicium-
99m are 140 keV, and the energy of X-rays from a
high-energy radiographic machine may be as high as
10 MeV.
C. X-RAY PRODUCTION
Radiation-producing devices produce X-rays by
accelerating electrons through an electrical voltage
potential and stopping them in a target. Many devices
that use a high voltage and a source of electrons produce
X-rays as an unwanted byproduct of device operation.
These are called incidental X-rays.
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Most X-ray devices emit electrons from a cathode,
accelerate them with a voltage, and allow them to hit an
anode, which emits X-ray photons.
i. Bremsstrahlung.
When electrons hit the anode, they decelerate or
brake emitting bremsstrahlung (meaning braking
radiation in German). Bremsstrahlung is produced
most effectively when small charged particles
interact with large atoms such as when electrons hit
a tungsten anode. However, bremsstrahlung can be
produced with any charged particles and any target.
For example, at research laboratories,
bremsstrahlung has been produced by accelerating
protons and allowing them to hit hydrogen.
Discuss types of radiation
produced.
ii. Characteristic X-Rays.
When electrons change from one atomic orbit to
another, characteristic X-rays are produced. The
individual photon energies are characteristic of the
type of atom and can be used to identify very small
quantities of a particular element. For this reason,
they are important in analytical X-ray applications at
research laboratories.
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D. EFFECT OF VOLTAGE AND CURRENT ON
PHOTON ENERGY AND POWER
It is important to distinguish between the energy of
individual photons in an X-ray beam and the total
energy of all the photons in the beam. It is also
important to distinguish between average power and
peak power in a pulsed X-ray device.
Typically, the individual photon energy is given in
electron volts (eV), whereas the power of a beam is
given in watts (W). An individual 100 keV photon has
more energy than an individual 10 keV photon.
However, an X-ray beam consists of a spectrum (a
distribution) of photon energies and the rate at which
energy is delivered by a beam is determined by the
number of photons of each energy. If there are many
more low energy photons, it is possible for the low
energy component to deliver more energy.
The photon energy distribution may be varied by
changing the voltage. The number of photons emitted
may be varied by changing the current.
i. Voltage.
The power supplies for many X-ray devices do not
produce a constant potential (D.C.) high voltage but
instead energize the X-ray tube with a time varying
or pulsating high voltage. In addition, since the
bremsstrahlung X-rays produced are a spectrum of
energies up to a maximum equal to the electron
accelerating maximum voltage, the
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accelerating voltage of the X-ray device is often
described in terms of the peak kilovoltage or kVp.
A voltage of 50 kVp will produce a spectrum of X-
ray energies with the theoretical maximum being 50
keV. The spectrum of energies is continuous from
the maximum to zero. However, X-ray beams are
typically filtered to minimize the low-energy
component. Low-energy X-rays are not useful in
radiography, but can deliver a significant dose.
Many X-ray devices have meters to measure
voltage. Whenever the voltage is on, a device can
produce some X-rays, even if the current is too low
to read.
ii. Current.
The total number of photons produced by an X-ray
device depends on the current, which is measured in
amperes, or amps (A). The current is controlled by
increasing or decreasing the number of electrons
emitted from the cathode. The higher the electron
current, the more X-ray photons are emitted from
the anode. Many X-ray devices have meters to
measure current. However, as mentioned above, X-
rays can be produced by voltage even if the current
is too low to read on the meter. This is sometimes
called dark current. This situation can cause
unnecessary exposure and should be addressed in
SOPs or work documents.
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iii. Determining Electrical Power.
Power, which is measured in watts (W), equals
voltage times current (P = V x I). For example, a 10
kVp device with a current of 1 mA uses 10 W of
power.
(Insert facility-specific examples for determining
electrical power.)
E. INTERACTION WITH MATTER
i. Scattering.
When X-rays pass through any material, some will
be transmitted, some will be absorbed, and some
will scatter. The proportions depend on the photon
energy, the type of material and its thickness.
X-rays can scatter off a target to the surrounding
area, off a wall and into an adjacent room, and over
and around shielding. A common mistake is to
install thick shielding walls around an X-ray source
but ignore the roof; X-rays can scatter off air
molecules over shielding walls to create a radiation
field known as skyshine. The emanation of X-rays
through and around penetrations in shielding walls
is called radiation streaming.
ii. Implications of Power and X-Ray Production.
When high-speed electrons strike the anode target,
most of their energy is converted to heat in the
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target, but a portion is radiated away as X-rays. As
stated previously, the electrical power of an
electrical circuit is given by:
P = V x I
P is the power in watts or joules/second, V is the
potential difference in volts, and I is the current in
amps.
The power developed in the anode of an X-ray tube
can be calculated using this relationship. Consider a
150 kilovolt (kVp) machine, with a current of 50
milliamps (ma).
P = [150,000 (V)] [0.050 (I)] = 7500 W.
This is about the same heat load as would be found
in the heating element of an electric stove. This
power is delivered over a very short period of time,
typically less than 1 second. More powerful X-ray
machines use higher voltages and currents and may
develop power as high as 50,000 W or more.
Cooling the anode is a problem that must be
addressed in the design of X-ray machines.
Tungsten is used because of its high melting
temperature, and copper is used because of its
excellent thermal conductivity. These elements may
be used together, with a tungsten anode being
embedded in a large piece of copper.
The percentage of the power transformed to X-rays
can be estimated by the following relationship:
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Fraction of incident electron energy transformed
into X-ray energy equals:
(7 X 10 -4) x Z x E
Where Z is the atomic number of the element (74
for tungsten) and E is the maximum energy of the
incoming electrons in MeV.
In this case, the fraction would be:
(7 X 10 -4) x 74 x 0.150 = 0.008
In the above example P is 7500 W. So the electron
energy incident upon the anode is:
7500 W = 7500 J/s Note: 1 W = 1 J/s
Then the energy transformed into X-rays would be
0.008 [7500] = 60 J/s.
1 J = 107 ergs, and 100 ergs/g = 1 rad.
So this X-ray energy represents:
6.0 x 108 ergs/sec.
If all this X-ray energy were deposited in 1 g of
tissue, the dose would be:
6.0 x 108 ergs/sec [1 rad/100ergs/g] =
6.0 x 106 rad/sec.
However, in practical applications X-ray beams are
filtered to remove softer X-rays not useful in
radiology, the X-ray pulse is much less than 1
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second, and the useful beam region is several cm
away from the anode target. These design features
lower the dose rates of the useful X-ray beam
significantly. The dose rate in a typical X-ray beam
is estimated in Module 103 section E iii.
iii. Filtration.
Low- and high-energy photons are sometimes
referred to as soft and hard X-rays, respectively.
Because hard X-rays are more penetrating, they are
more desirable for radiography (producing a
photograph of the interior of the body or a piece of
apparatus). Soft X-rays are less useful for
radiography because they are largely absorbed near
the surface of the body being X-rayed. However,
there are medical applications where soft X-rays are
useful.
A filter, such as a few millimeters of aluminum, or
copper may be used to harden the beam by
absorbing most of the low-energy photons. The
remaining photons are more penetrating and are
more useful for radiography.
In X-ray analytical work (X-ray diffraction and
fluorescence), filters with energy selective
absorption edges are not used to harden the beam,
but to obtain a more monochromatic beam (a beam
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with predominantly one energy). By choosing the
right element, it is possible to absorb a band of high
energy photons preferentially over an adjacent band
of low energy photons.
(Insert facility-specific examples of filtration.)
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III. MODULE 103 - BIOLOGICAL EFFECTS
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the participants
should understand the biological effects of X-rays
and the importance of protective measures for
working with or around X-rays.
ii. Objectives.
Following self-study and/or classroom review, the
participants will be able to:
1. Outline the early history of X-rays and the
consequences of working with or around
X-rays without protective measures.
2. Identify factors that determine the biological
effects of X-ray exposure.
3. State the differences between thermal and X-
ray burns.
4. Identify the signs and symptoms of an acute
dose from X-rays.
5. Explain the effects of chronic exposure to
X-rays.
6. Identify the difference between somatic and
heritable effects.
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B. EARLY HISTORY OF X-RAYS
i. Discovery of X-Rays.
X-rays were discovered in 1895 by German scientist
Wilhelm Roentgen. On November 8, 1895,
Roentgen was investigating high-voltage electricity
and noticed that a nearby phosphor glowed in the
dark whenever he switched on the apparatus. He
quickly demonstrated that these unknown “x” rays,
as he called them, traveled in straight lines,
penetrated some materials, and were stopped by
denser materials. He continued experiments with
these “x” rays and eventually produced an X-ray
picture of his wife's hand showing the bones and her
wedding ring. On January 1, 1896, Roentgen
mailed copies of this picture along with his report to
fellow scientists.
By early February 1896, the first diagnostic X-ray in
the United States was taken, followed quickly by the
first X-ray picture of a fetus in utero. By March of
that year, the first dental X-rays were taken. In that
same month, French scientist Henri Becquerel was
looking for fluorescence effects from the sun, using
uranium on a photographic plate. The weather
turned cloudy so he put the uranium and the
photographic plate into a drawer. When Becquerel
developed the plates a few weeks later,
he realized he had made a new discovery. His
student, Marie Curie, named it radioactivity.
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ii. Discovery of Harmful Effects.
Because virtually no protective measures were used
in those early days, it was not long after the
discovery of X-rays before people began to learn
about their harmful effects. X-ray workers were
exposed to very large doses of radiation, and skin
damage from that exposure was observed and
documented early in 1896. In March of that year,
Thomas Edison reported eye injuries from working
with X-rays. By June, experimenters were being
cautioned not to get too close to X-ray tubes. By the
end of that year, reports were being circulated about
cases of hair loss, reddened skin, skin sloughing off,
and lesions. Some X-ray workers lost fingers, and
some eventually contracted cancer. By the early
1900s, the potential carcinogenic effect of X-ray
exposure in humans had been reported.
Since that time, more than a billion dollars has been
spent in this country alone on research investigating
the biological effects of ionizing radiation. National
and international agencies have formed to aid in the
standardization of the uses of X-rays to ensure safer
practices.
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C. BIOLOGICAL EFFECTS OF IONIZATION
X-rays can penetrate into the human body and ionize
atoms. This process creates radicals that can break or
modify chemical bonds within critical biological
molecules. This can cause cell injury, cell death, and
may be the cause of radiation-induced cancer. The
biological effect of radiation depends on several factors
(discussed below) including the dose and dose rate.
Objective 3
In some cases, altered cells are able to repair the
damage. However, in other cases, the effects are passed
to daughter cells through cell division and after several
divisions can result in a group of cells with altered
characteristics. These cells may result in tumor or
cancer development. If enough cells in a body organ are
injured or altered, the functioning of the organ can be
impaired.
D. FACTORS THAT DETERMINE BIOLOGICAL
EFFECTS
Several factors contribute to the biological effects of
X-ray exposure, including:
• Dose rate.
• Total dose received.
• Energy of the radiation.
• Area of the body exposed.
• Individual sensitivity.
• Cell sensitivity.
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i. Dose Rate.
The rate of dose delivery is commonly categorized
as acute or chronic. An acute dose is received in a
short period (seconds to days); a chronic dose is
received over a longer period (months to years).
For the same total dose, an acute dose is more
damaging than a chronic dose. It is believed that
this effect is due to the ability of cells to repair
damage over time. With an acute dose, a cell may
receive many “hits” without sufficient time to repair
damage.
ii. Total Dose Received.
The higher the total amount of radiation received,
the greater the biological effects. The effects of a
whole body dose of less than 25 rem are generally
not clinically observable. For doses of 25-100 rem
there are generally no symptoms, but a few persons
may exhibit mild prodromal symptoms, such as
nausea and anorexia. Bone-marrow damage may be
noted, and a decrease in red and white blood-cell
counts and platelet count should be discernable.
100-300 rem may result in mild to severe nausea,
malaise, anorexia, infection. Hematologic damage
will be more severe. Recovery is probable, though
not assured.
Although effects of lower doses have not been
observed directly, it is conservatively assumed that
the higher the total dose, the greater the risk of
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contracting fatal cancer without consideration of a
threshold for effects. This conservative assumption
is sometimes called the “linear no threshold”
relationship of health effects to dose.
iii. Energy of the Radiation.
The energy of X-rays can vary from less than 1 keV
up to more than 10 MeV. The higher the energy of
the X-ray, the more penetrating it will be into body
tissue.
Lower energy X-rays are largely absorbed in the
skin. They can cause a significant skin dose but
may contribute little dose to the whole body
(depending on energy).
iv. Area of the Body Exposed.
Just as a burn to a large portion of the body is more
damaging than a burn confined to a smaller area, so
also is a radiation dose to the whole body more
damaging than a dose to only a small area. In
addition, the larger the area, the more difficult it is
for the body to repair the damage.
v. Individual Sensitivity.
Some individuals are more sensitive to radiation
than others. Age, gender, and overall health can
have an effect on how the body responds to
radiation exposure.
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vi. Cell Sensitivity.
Some cells are more sensitive to radiation than
others. Cells that are more sensitive to radiation are
radiosensitive; cells that are less sensitive to
radiation are radioresistant.
The law of Bergonie and Tribondeau states:
The radiosensitivity of a tissue is directly
proportional to its reproductive capacity and
inversely proportional to its degree of
differentiation.
It is generally accepted that cells tend to be
radiosensitive if they are:
1) Cells that have a high division rate
2) Cells that have a high metabolic rate
3) Cells that are of a non-specialized type
4) Cells that are well nourished
The following are radiosensitive tissues:
1) Germinal
2) Hematopoietic
3) Epithelium of the skin
4) Epithelium of the gastrointestinal tract
The following are radioresistant tissues:
1) Bone
2) Liver
3) Kidney
4) Cartilage
5) Muscle
6) Nervous system tissue
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E. SOMATIC EFFECTS
Somatic effects are biological effects that occur in the
individual exposed to radiation. Somatic effects may
result from acute or chronic doses of radiation.
i. Early Acute Somatic Effects.
The most common injury associated with the
operation of X-ray analysis equipment occurs when
a part of the body, usually a hand, is exposed to the
primary X-ray beam. Both X-ray diffraction and
fluorescence analysis equipment generate
high-intensity, low-energy X-rays that can cause
severe and permanent injury if any part of the body
is exposed to the primary beam.
The most common injury associated with the
operation of industrial X-ray equipment occurs
when an operator is exposed to the primary X-ray
beam for as little as a few seconds.
These types of injuries are sometimes referred to as
radiation burns.
ii. Difference Between X-Ray Damage and Thermal
Burns (Key Item).
Objective 3
Most nerve endings are near the surface of the skin,
so they give immediate warning of heat or a surface
thermal burn such as the participants might receive
from touching a high-temperature object. In
contrast, the body can not immediately feel
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exposure to X-rays. X-ray damage has historically
been referred to as a radiation “burn,” perhaps
because the reaction of the skin after the radiation
exposure may appear similar to a thermal burn. In
fact, X-ray damage to the tissue is very different
from a thermal burn and there is no sensation or
feeling as the damage is occurring.
In radiation burns, the radiation does not harm the
outer, mature, nondividing skin layers. Rather, most
of the X-rays penetrate to the deeper, basal skin
layer, damaging or killing the rapidly dividing
germinal cells that are otherwise destined to replace
the outer layers that slough off. Following this
damage, as the outer cells are naturally sloughed off,
they are not replaced. Lack of a fully viable basal
layer of cells means that X-ray burns are slow to
heal, and in some cases may never heal. Frequently,
such burns require skin grafts. In some cases,
severe X-ray burns have resulted in gangrene and
amputation.
An important variable is the energy of the radiation
because this determines the depth of penetration in a
given material. Heat radiation is infrared, typically
1 eV; sunburn is caused by ultraviolet rays, typically
4 eV; and X-rays are typically 10 - 100 keV, which
are capable of penetrating to the depth of the basal
layer of the skin.
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iii. Early Signs and Symptoms of Accidental Exposure
to X-Rays.
Note: the doses discussed in this section are
localized shallow skin doses and/or localized doses,
but not whole body doses. Whole body deep doses
of this magnitude would likely be fatal. Accidental
exposures from RPDs are generally localized to a
small part of the body.
~600 rad. An acute dose of about 600 rad to a part
of the body causes a radiation burn equivalent to a
first-degree thermal burn or mild sunburn.
Typically there is no immediate pain that would
cause the participants to pull away, but a sensation
of warmth or itching occurs within a few hours after
exposure. An initial reddening or inflammation of
the affected area usually appears several hours after
exposure and fades after a few more hours or days.
The reddening may reappear as late as two to three
weeks after the exposure. A dry scaling or peeling
of the irradiated portion of the skin is likely to
follow.
If the participants have been working with or around
an X-ray device and the participants notice an
unexplained reddening of the skin, notify the
supervisor and the Occupational Medicine Group.
Aside from avoiding further injury and guarding
against infection, further medical treatment will
probably not be required and recovery should be
fairly complete.
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An acute dose of 600 rad delivered to the lens of the
eye causes a cataract to begin to form.
~1,000 rad. An acute dose of about 1,000 rad to a
part of the body causes serious tissue damage
similar to a second-degree thermal burn. First
reddening and inflammation occur, followed by
swelling and tenderness. Blisters will form within
one to three weeks and will break open, leaving raw
painful wounds that can become infected. Hands
exposed to such a dose become stiff, and finger
motion is often painful. If the participants develop
symptoms such as these, seek immediate medical
attention to avoid infection and relieve pain.
~2,000 rad. An acute dose of about 2,000 rad to a
part of the body causes severe tissue damage similar
to a scalding or chemical burn. Intense pain and
swelling occur within hours. For this type of
radiation burn, seek immediate medical treatment to
reduce pain. The injury may not heal without
surgical removal of exposed tissue and skin grafting
to cover the wound. Damage to blood vessels also
occurs.
~3,000 rad. An acute dose of 3,000 rad to a part of
the body completely destroys tissue and surgical
removal is necessary.
It does not take long to get a significant dose from
an X-ray unit. The dose rate from an X-ray unit can
be estimated from the Health Physics and
Radiological Health Handbook, 1992 edition
Table 10.1.1.
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Example: Assume:
2.5 mm Al filter
100 kVp
100 mA
1 sec exposure
30 cm distance
Dose estimate (in air, assuming electron
equilibrium): 12.8 Rad
(Compare these values to facility-specific equipment or
examples.)
iv. Latent Effects from Radiation Exposure.
The probability of a latent effect appearing several
years after radiation exposure depends on the
amount of the dose. The higher the dose, the greater
the risk of developing a health effect. When an
individual receives a large accidental exposure and
the prompt effects of that exposure have been dealt
with, there still remains a concern about latent
effects years after the exposure. Although there is
no unique disease associated with exposure to
radiation, there is a risk of the possibility of
developing fatal cancer. The higher the
accumulated dose, the greater is the risk of health
effect, based on the linear-no threshold model.
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v. Risk of Developing Cancer from Low Doses.
It is not possible to absolutely quantify the risk of
cancer from low doses of radiation because the
health effects cannot be distinguished from the
relatively large natural cancer rate (approximately
20 percent of Americans die from cancer). The risk
of health effects from low doses must be inferred
from effects observed from high acute doses. The
risk estimates for high doses were developed
through studies of Japanese atomic bomb survivors,
uranium miners, radium watch-dial painters, and
radiotherapy patients. These risk factors are applied
to low doses with a reduction factor for chronic
exposures.
Refer to BEIR V Report, NCRP
116, and ICRP60
However, below 10 rem, health effects are too small
to measure. The dose limits and administrative
control levels listed in Module 101 have been
established so that the risk to workers is on a par
with the risks to workers in safe industries,
assuming a linear relationship between dose and
health effects. However, these are maximum values
and the ALARA principle stresses maintaining
doses well below these values.
vi. Effects of Prenatal Exposure (Teratogenic Effects).
The embryo/fetus is especially sensitive to radiation.
The embryo is sensitive to radiation because of the
relatively high replication activity of the cells and
the large number of nonspecialized cells.
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Workers who become pregnant are encouraged to
declare their pregnancy in writing to their
supervisors. The dose limit for the embryo/fetus of
a declared pregnant worker is 500 mrem during the
term of the pregnancy; 10 CFR 835.206 (b) states
“Substantial variation above a uniform exposure
rate that would satisfy the limits provided in 10
CFR835.206 (a) [i.e., 500 mrem for term of
pregnancy] shall be avoided.”
10 CFR 835.206
F. HERITABLE EFFECTS
Heritable effects are biological effects that are inherited
by children from their parents at conception. Irradiation
of the reproductive organs can damage cells that contain
heritable information passed on to offspring.
Radiation-induced hereditary effects have been observed
in large-scale experiments with fruit flies and mice
irradiated with large doses of radiation. Such health
effects have not been observed in humans. Based on the
animal data, however, the conservative assumption is
made that radiation-induced hereditary effects could
occur in humans.
Radiation-induced heritable effects do not result in
genetic diseases that are uniquely different from those
that occur naturally. Extensive observations of the
children of Japanese atomic bomb survivors have not
revealed any statistically significant hereditary health
effects.
Note: Congenital (teratogenic) effects are not heritable
effects. Congenital effects are not inherited; they are
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caused by the action of agents such as drugs, alcohol,
radiation, or infection to an unborn child in utero.
Congenital or teratogenic effects did occur in children
who were irradiated in utero by the atomic bombs at
Hiroshima or Nagasaki.
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IV. MODULE 104 - RADIATION DETECTION
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the participants
should understand which radiation-monitoring
instruments and which personnel-monitoring
devices are appropriate for detecting X-rays.
ii. Objectives.
Following self-study and/or classroom review, the
participants will be able to:
1. Identify the instruments used for X-ray
detection and
2. Identify the devices used for personnel
monitoring.
B. RADIATION SURVEYS
Radiation protection surveys should be conducted on all
new or newly installed X-ray devices by the X-Ray
Device Control Office (or facility-specific equivalent)
and repeated at a frequency determined by site policies.
C. X-RAY DETECTION INSTRUMENTS
External exposure controls used to minimize the dose
equivalent to workers are based on the data taken with
Objective 4
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portable radiation-monitoring instruments during a
radiation survey. An understanding of these instruments
is important to ensure that the data obtained are accurate
and appropriate for the source of radiation.
Note: Emphasize that
completion of this training will
not qualify individuals to use
these instruments, specific
instrument training is required.
Many factors can affect how well the survey
measurement reflects the actual conditions, including
C Selection of the appropriate instrument based on
type and energy of radiation and on radiation
intensity.
C Correct operation of the instrument based on the
instrument operating characteristics and limitations.
C Calibration of the instrument to a known radiation
field similar in type, energy, and intensity to the
radiation field to be measured.
i. Instruments Used for X-Ray Detection
It is important to distinguish between detection and
measurement of X-rays. Equipment users often use
a detector to detect the presence of X-rays, for
example, to verify that the device is off before entry
into the area. The measurement of X-rays is
normally the job of a qualified Radiological Control
Technician.
Measurement of radiation dose rates and surveys of
record require an instrument that reads roentgen or
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rem (R/hour, mR/hour, rem/hour, mrem/hour) rather
than counts per minute (cpm) or disintegrations per
minute (dpm). Ion chambers measure energy
deposited and are good instruments for measuring
X-ray radiation dose levels.
Instruments such as Geiger-Mueller (GM) counters
are effective for detection of radiation because of
their good sensitivity. However, because both low-
energy and high-energy photons discharge the
counter, GM counters do not quantify a dose well.
A thin-window GM counter is the instrument of
choice for the detection of X-rays. However, this is
not the instrument of choice for measurement of X-
ray dose.
ii. Facility-Specific Instrumentation
(Insert facility-specific information on
instrumentation, as appropriate.)
D. PERSONNEL-MONITORING DEVICES
Note: X-ray leakage from RPD housings or shielding
may be a narrow beam that is difficult to detect and may
not be recorded by personnel monitoring devices.
i. Whole Body Dosimeters.
Operators of intentional X-ray devices usually wear
dosimetry such as thermoluminescent dosimeters
(TLDs) film or badges. These dosimeters can
accurately measure radiation doses as low as 10
Objective 2
10 CFR 835.801(d)
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mrem and are used to determine the dose of record.
However, they must be sent to a processor to be
read. Therefore, the exposed individual may not be
aware of his exposure until the results have been
reported (typically 1 day - several weeks).
There are several precautions that are important in
the use of dosimeters. Dosimeters should be worn
in a location that will record a dose representative of
the trunk of the body. Standard practice is to wear a
dosimeter between the neck and the waist, but in
specific situations such as nonuniform radiation
fields, special considerations may apply. Some
dosimeters have a required orientation with a
specific side facing out.
(Insert facility-specific information on dosimetry, as
appropriate.)
ii. Extremity Dosimeters.
Finger-ring and wrist dosimeters may be used to
assess radiation dose to the hands.
(Insert facility-specific information on dosimetry, as
appropriate.)
iii. Pocket Dosimeters.
Pocket ionization chambers, such as pencil
dosimeters or electronic dosimeters, are used in
radiological work. In contrast to TLDs, they give
an immediate readout of the radiation dose. Pencil
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dosimeters are manufactured with scales in several
different ranges, but the 0B500 mR range, marked
in increments of 20 mR, is often used. The dose is
read by observing the position of a hairline that
moves upscale in proportion to dose. Pocket
dosimeters are supplemental and used primarily as
radiological worker management tools. They are
not typically used for determining the dose of record
required by 10 CFR 835.
iv. Alarming Dosimeters.
In higher dose-rate areas, an alarming dosimeter
may be used to provide an audible warning of
radiation. This contributes to keeping doses
ALARA by increasing a worker's awareness of the
radiation.
Specific applications may require special
considerations. For example, low-energy X-rays
will not penetrate the walls of some dosimeters.
Flash X-ray devices produce a very short pulse that
is not correctly measured by most dose-rate
instruments.
(Insert facility-specific information as appropriate.)
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V. MODULE 105 - PROTECTIVE MEASURES
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the participants
should understand protective measures that restrict
or control access to X-ray areas and devices or warn
of X-ray hazards, and should be able to use work
documents that provide specific procedures to
ensure safe operation of X-ray devices.
ii. Objectives.
Following self-study and/or classroom review, the
participants will be able to:
1. Identify and state specific administrative and
engineered controls.
2. Identify and state specific radiological
postings.
3. Define “interlocks”, as applicable.
4. Explain specific shielding practices.
5. Identify typical RPD warning devices.
6. Outline site-specific work documents.
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B. RADIOLOGICAL CONTROLS
To control exposure to radiation, as well as maintain
exposure ALARA, access to radiological areas is
restricted by a combination of administrative and
engineering controls.
Objective 6
10 CFR 835.501-502
10 CFR 835.601-603
10 CFR 835.1001-1003
Examples of administrative controls include:
• Posting.
• Warning signals and labels.
• Work control documents such as SOPs and RWPs.
Examples of engineered controls include:
• Interlocks.
• Shielding.
For high-radiation areas where radiation levels exist
such that an individual could exceed a deep dose
equivalent of 1 rem in any 1 hour at 30 cm from the
source or surface that the radiation penetrates, one or
more of the following features shall be used to control
exposure:
10 CFR 835.502
• A control device that prevents entry.
• A device that prevents use of the radiation source
while personnel are present.
• A device that energizes a visible and audible alarm.
• Locked entry ways.
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• Continuous direct or electronic surveillance to
prevent unauthorized entry.
• A device that generates audible and visual alarms in
sufficient time to permit evacuation.
In addition to the above measures, for very high
radiation areas (areas accessible to individuals in which
radiation levels could result in an individual receiving a
dose in excess of 500 rads in 1 hour), additional
measures shall be implemented to ensure individuals are
not able to gain access.
C. RADIOLOGICAL POSTINGS
i. Purpose of Posting.
The two primary reasons for radiological posting
are:
1. To inform workers of the radiological
conditions and
2. To inform workers of the entry requirements
for an area.
ii. General Posting Requirements.
1. Signs contain the standard radiation
symbol colored magenta or black on a
yellow background.
10 CFR 835.601(c)
2. Signs shall be clearly and conspicuously
posted to alert personnel to the presence
10 CFR 835.601(d)
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of radiation. Signs may also include
radiological protection instructions.
3. If more than one radiological condition
exists in the same area, each condition
should be identified.
4. Rope, tape, chain, or similar barrier
material used to designate radiological
areas should be yellow and magenta.
5. Physical barriers should be placed so that
they are clearly visible from all accessible
directions and at various elevations.
6. Posting of doors should be such that the
postings remain visible when doors are
open or closed.
7. Radiological postings that indicate an
intermittent radiological condition should
include a statement specifying when the
condition exists, such as
“CAUTION, RADIATION AREA
WHEN RED LIGHT IS ON.”
For a Radiation Area, wording on the
posting shall include the words:
“CAUTION, RADIATION AREA.”
For a High Radiation Area, wording on
the posting shall include the words:
10 CFR 835.603(a)
“DANGER, HIGH RADIATION AREA.” 10 CFR 835.603(b)
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For a Very High Radiation Area, wording
on the posting shall include the words:
“GRAVE DANGER, VERY HIGH
RADIATION AREA.”
10 CFR 835.603(c)
The same posting requirements apply for
X-ray or gamma radiation as for any other
type of radiation. Areas controlled for
radiological purposes are posted according
to the radiation dose rates in the area, as
shown in the following table. These
definitions are standard throughout the
DOE complex.
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Areas
Defining Condition
Controlled Area
Means any area to which access is managed to
protect individuals from exposure to radiation
and/or radioactive material.
Radiation Area
Means any area accessible to individuals in
which radiation levels could result in an
individual receiving a deep dose equivalent in
excess of 0.005 rem (0.05 millisievert) in 1 hour
at 30 centimeters from the source or from any
surface that the radiation penetrates.
High Radiation Area
Means any area accessible to individuals, in
which radiation levels could result in an
individual receiving a deep dose equivalent in
excess of 0.1 rem (0.001 sievert) in 1 hour at 30
centimeters from the radiation source or from
any surface that the radiation penetrates.
Very High Radiation Area
Means any area accessible to individuals in
which radiation levels could result in an
individual receiving an absorbed dose in excess
of 500 rads (5 grays) in 1 hour at 1 meter from a
radiation source or from any surface that the
radiation penetrates.
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(Insert facility-specific information on posting, labeling,
and entry requirements, as applicable.)
D. INTERLOCKS
Fail-safe interlocks should be provided on doors and
access panels of X-ray devices so that X-ray production
is not possible when they are open. A fail-safe interlock
is designed so that any failure that can reasonably be
anticipated will result in a condition in which personnel
are safe from excessive radiation exposure.
Guidance from the ANSI standards is that interlocks
should be tested by the operating group at least every six
months. The interlock test procedure may be locally
specified, but typically is as follows:
Refer to ANSI N43.2
1. Energize the X-ray tube.
2. Open each door or access panel one at a time.
3. Observe the X-ray warning light or current meter at
the control panel.
4. Record the results in a log.
(Insert facility-specific information, as appropriate.)
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E. SHIELDING
i. Analytical Systems.
For analytical X-ray machines, such as X-ray
fluorescence and diffraction systems, the
manufacturer provides shielding in accordance
with ANSI N43.2. However, prudent practice
requires that any device or source that involves
radiation should be surveyed to determine the
adequacy of the shielding.
Enclosed beam systems have sufficient shielding
so that the dose rate at 5 cm from its outer surface
does not exceed 0.25 mrem per hour under normal
operating conditions. The dose rate may be
difficult to evaluate. According to ANSI N43.2,
this requirement is met if the shielding is at least
equal to the thickness of lead specified in the
following table for the maximum rated anode
current and potential.
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MINIMUM SHIELDING TO KEEP THE DOSE RATE BELOW 0.25 MREM/HOUR
ANODE CURRENT
MILLIMETERS OF LEAD
(MA)
50 KVP
70 KVP
100 KVP
20
1.5
5.6
7.7
40
1.6
5.8
7.9
80
1.6
5.9
--
160
1.7
--
--
Lesson Plan Instructor’s Notes
ii. Industrial Systems.
Some industrial X-ray systems, such as the
cabinet X-ray systems used for airport
security, are completely enclosed in an
interlocked and shielded cabinet. Larger
systems such as medical X-ray units are
enclosed in a shielded room to which access
is restricted. Shielding for X-ray rooms is
conservatively designed to handle the
expected workload conditions.
Radiological control technicians (RCTs)
periodically verify that the shielding
integrity has not deteriorated.
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X-Ray Device Control Office (or facility-
specific equivalent) personnel develop
recommendations for shielding based on the
following information:
1. Shielding the primary X-ray beam
and
2. Shielding the areas not in the line
of the primary beam from leakage
and scattered radiation.
There are independent analyses for
each component to derive an
acceptable shield thickness.
For example, the calculation used
for the primary X-ray beam
depends on:
- Peak voltage.
- The maximum permissible
exposure rate to an individual.
- The workload of the machine
expressed in mA min/wk.
- The use factor: the fraction of
the workload during which the
useful beam is pointed in a
direction under consideration.
- The occupancy factor that takes
into account the fraction of
time that an area outside the
barrier is likely to be occupied
by a given individual.
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- The distance from the target of
the tube to the location under
consideration.
The calculation uses conservative
values and derives a value (K) that
is used with graphs to determine
shield thickness of a given type of
material (e.g., lead or concrete).
F. WARNING DEVICES
Operators should be aware of the status of the X-
ray tube. Indicators that warn of X-ray production
typically include:
• A current meter on the X-ray control panel.
• A warning light labeled X-RAYS ON near or
on the control panel.
• Warning light labeled X-RAYS ON near any
X-ray room door.
These warning lights or indicators are activated
automatically when power is available for X-ray
production.
For X-ray systems with an open beam in a shielded
room, evacuation warning signals and signs must
be activated at least 20 seconds before X-ray
production can be started. Any person who is
inside the room when warning signals come on
should immediately leave the room and activate the
panic or scram switch on the way out. This is an
emergency system designed to shut down the X-ray
system immediately.
(Insert facility-specific information.)
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G. WORK DOCUMENTS
(Note: this section is provided only as an example
and should be replaced with facility-specific
information.)
Objective 6
i. Typical Standard Operating Procedures
(SOP).
An X-ray device has a procedure such as an
SOP to promote safe and efficient
operation. SOPs typically include the
following:
1. Description/specification of the X-
ray device and the purpose for
which it is used.
2. Normal X-ray parameters (peak
power, current, exposure time, X-
ray source-to-film distance, etc.).
3. Procedures for proper sample
preparation, alignment procedures,
or handling of object to be
radiographed.
4. Description of all safety hazards
(electrical, mechanical, explosive,
as well as radiation hazards)
associated with the operation of
the X-ray device.
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5. Description of the safety features
such as interlocks and warning
signals and any other safety
precautions.
6. Procedures for performing
interlock tests and the
recommended frequency of such
tests.
7. Required operator training and
dosimetry.
8. Posting of signs and labels.
9. X-ray device safety checklist
(items to be checked periodically
or each day before use).
10. Actions to take in the event of an
abnormal occurrence or
emergency.
11. Requirements for the use of a
radiation-monitoring instrument
upon entry into the Radiation Area
to verify that the X-ray beam is off
are specified in ANSI N43.3 for
some industrial X-ray devices.
Specify which types of X-ray
devices require this measure at
your facility (e.g., only open
systems).
X-Ray Device Control Office personnel (or
facility-specific equivalent) review each
SOP to verify that it establishes appropriate
safety practices and they can assist the
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operating groups in preparing or modifying
an SOP. The current SOP should be kept
near the X-ray device.
Operating groups are responsible for
ensuring that the operator becomes familiar
with and uses the SOP. The operator is
responsible for following the SOP.
ii. Radiological Work Permits (RWPs).
RWPs are used to establish radiological
controls for entry into radiological areas.
They serve to:
1. Inform workers of area
radiological conditions.
2. Inform workers of entry
requirements into the areas.
3. Provide a means to relate radiation
doses to specific work activities.
A job-specific RWP is used to control
nonroutine operations or work areas with
changing radiological conditions.
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RWPs are typically used in conjunction
with X-ray devices when any of the
following situations exist:
1. A compliance label for a newly
acquired X-ray device cannot be
issued because the SOP for that
device has not yet been written
and approved.
2. A portable X-ray device or open
system used only for a short period
that does not warrant writing an
SOP.
3. An event that requires an operator
enter the area when the X-ray
beam is on.
An example of a non-routine
entry is one that requires operator
entry with the beam on, creating
a radiation area or high radiation
area. Include facility-specific
examples.
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VI. MODULE 106 - X-RAY GENERATING DEVICES
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the
participants should understand the
categories of X-ray producing devices and
the hazards associated with each.
(Note: Module 106 reflects the guidance of
the ANSI Standards N43.2 and N43.3.
Insert facility-specific information as
appropriate.)
ii. Objectives.
Following self-study and/or review, the
participants will be able to:
1. Contrast incidental and intentional
X-ray devices.
2. Contrast analytical and industrial
X-ray devices.
3. Identify open and enclosed beam
installations.
4. Describe the safety features
essential for operation of industrial
and analytical systems.
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B. INCIDENTAL AND INTENTIONAL DEVICES
X-ray systems are divided into two broad
categories: intentional and incidental.
Objective 7
An incidental X-ray device produces X-rays that
are not wanted or used as a part of the designed
purpose of the machine. Shielding on an incidental
X-ray device should preclude significant exposure.
Examples of incidental systems are computer
monitors, televisions, electron microscopes, high-
voltage electron guns, electron beam welding
machines, electrostatic separators, and Jennings
switches.
An intentional X-ray device is designed to generate
an X-ray beam for a particular use. Examples
include X-ray diffraction and fluorescence analysis
systems, flash X-ray systems, medical X-ray
machines, and industrial cabinet and noncabinet X-
ray equipment. Intentional X-ray devices are
further divided into two subcategories: analytical
and industrial.
ANSI has issued two standards that provide
radiation safety guidelines for X-ray systems.
ANSI N43.2 applies to non-medical X-ray systems
and ANSI N43.3 applies to X-ray diffraction and
fluorescence industrial systems.
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C. INCIDENTAL X-RAY DEVICES
i. Exempt Shielded Systems.
Exempt shielded systems are defined in the
ANSI Standard N43.3. Electron
microscopes and other systems that are
exempt shielded are inherently safe, and
require review only on purchase or
modification. The exposure rate during any
phase of operation of these devices at the
maximum-rated continuous beam current
for the maximum-rated accelerating
potential should not exceed 0.5 mrem/hour
at 2 inches (5 cm) from any accessible
external surface.
(Add facility-specific examples.)
ii. Other Devices.
At a research laboratory, many devices
produce incidental X-rays. Any device that
combines high voltage and a vacuum could,
in principle, produce X-rays. For example,
a television or computer monitor generates
incidental X-rays, but in modern designs the
intensity is small, much less than 0.5
mrem/hour.
Occasionally, this hazard is recognized only
after the device has operated for some time.
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If the participants suspect an X-ray hazard,
contact an RCT or the X-Ray Device
Control Office (or facility-specific
equivalent) to survey the device.
(Add facility-specific examples.)
D. INTENTIONAL ANALYTICAL X-RAY
DEVICES
i. Analytical X-Ray Devices.
Analytical X-ray devices use X-rays for
diffraction or fluorescence experiments.
These research tools are normally used in
materials science. ANSI N43.2 defines two
types of analytical X-ray systems: enclosed
beam and open beam.
The following safety features are common
to both systems:
1. A fail-safe light or indicator is
installed in a conspicuous location
near the X-ray tube housing. These
indicators are energized
automatically and only when the
tube current flows or high voltage
is applied to the X-ray tube.
2. Accessories to the equipment have
a beam stop or other barrier.
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3. Shielding is provided.
(Add facility-specific examples.)
ii. Enclosed-Beam System.
In an enclosed-beam system, all possible X-
ray paths (primary and diffracted) are
completely enclosed so that no part of a
human body can be exposed to the beam
during normal operation. Because it is
safer, the enclosed-beam system should be
selected over the open-beam system
whenever possible.
The following safety features are specified
by ANSI N43.2 for an enclosed-beam X-ray
system:
1. The sample chamber door or other
enclosure should have a fail-safe
interlock on the X-ray tube high-
voltage supply or a shutter in the
primary beam so that no X-ray
beam can enter the sample
chamber while it is open.
2. X-ray tube, sample, detector, and
analyzing crystal (if used) must be
enclosed in a chamber or coupled
chambers that cannot be entered
by any part of the body during
normal operation.
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3. Radiation leakage measured at
2 inches (5 cm) from any outer
surface must not exceed
0.25 mrem/hour during normal
operation.
(Add facility-specific examples.)
iii. Open-Beam System.
According to ANSI N43.2, a device that
does not meet the enclosed-beam standards
is classified as an open-beam system. In an
open-beam system, one or more X-ray
beams are not enclosed, making exposure of
human body parts possible during normal
operation. The open-beam system is
acceptable for use only if an enclosed beam
is impractical because of any of the
following reasons:
1. A need for frequent changes of
attachments and configurations.
2. A need for making adjustments
with the X-ray beam energized.
3. Motion of specimen and detector
over wide angular limits.
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4. The examination of large or bulky
samples.
The following safety features are essential
in an open-beam X-ray system:
1. Each port of the X-ray tube
housing must have a beam shutter.
2. All shutters must have a
conspicuous SHUTTER OPEN
indicator of fail-safe design.
3. Shutters at unused ports should be
mechanically or electrically
secured to prevent casual opening.
4. Special rules apply when the
accessory setup is subject to
change as is the case with powder
diffraction cameras. In these cases,
the beam shutter must be
interlocked so the port will be
open only when the accessory is in
place.
5. Exposure rates adjacent to the
system must not exceed
2.5 mrem/hour at 5 cm from the
surface of the housing.
6. A guard or interlock must prevent
entry of any part of the body into
the primary beam.
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(Insert facility-specific information if
system definitions differ from the above.)
E. INTENTIONAL INDUSTRIAL X-RAY
DEVICES
i. Industrial X-Ray Devices.
Industrial X-ray devices are used for
radiography, for example, to take pictures
of the inside of an object as in an X-ray of a
pipe weld or to measure the thickness of
material. ANSI standard N43.3 defines five
classes of industrial X-ray installations:
cabinet, exempt shielded, shielded,
unattended, and open.
(Add facility-specific examples.)
ii. Cabinet X-ray Installation.
A cabinet X-ray installation is similar in
principle to the analytical enclosed beam
system. The X-ray tube is installed in an
enclosure (cabinet) that contains the object
being irradiated, provides shielding, and
excludes individuals from its interior during
X-ray generation. A common example is
the X-ray device used to inspect carry-on
baggage at airline terminals. Certified
cabinet X-ray systems comply with the
regulations of 21 CFR 1020.40.
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Exposure rates adjacent to a cabinet X-ray
system shall not exceed 2 mrem/hour.
(Add facility-specific examples.)
iii. Exempt Shielded Installation.
An exempt shielded facility or installation is
similar to a cabinet X-ray installation. It
provides a high degree of inherent safety
because the protection depends on passive
shielding and not on compliance with
procedures. This type does not require
restrictions in occupancy since passive
shielding is sufficient. The low allowable
dose equivalent rate of 0.5 mrem in any 1
hour at 5 cm from the accessible surface of
the enclosure for this class of installation
necessitates a high degree of installed
shielding surrounding the X-ray device.
(Add facility-specific examples.)
iv. Shielded Installation.
A shielded installation has less shielding
than exempt shielded. This is a cost
advantage for fixed installations,
particularly for high-energy sources where
the reduction in shielding may result in
significant savings. However, there is more
reliance on protective measures such as
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warning lights, posting, and procedures.
However, the posting and access control
requirements of 10 CFR 835 apply. Any
High Radiation Area must be appropriately
controlled and any Radiation Area must be
defined and posted.
(Add facility-specific examples.)
v. Unattended Installation.
An unattended installation consists of
equipment designed and manufactured for a
specific purpose and does not require
personnel in attendance for its operation.
Steps must be taken to ensure that the dose
to personnel is less than 100 mrem/year.
However, a short term limit of 2 mrem/hour
may be used provided the expected dose to
personnel is less than 100 mrem/year.
(Add facility-specific examples.)
vi. Open Installation
An open installation has X-ray paths that
are not enclosed. An example would be a
portable X-ray machine outdoors in an
emergency response situation, with the X-
ray tube not enclosed inside a shielded
room. This class is acceptable for use only
if operational requirements prevent the use
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of one of the other classes. Its use is limited
mainly to mobile and portable equipment
where fixed shielding cannot be used. The
protection of personnel and the public
depends almost entirely on strict adherence
to safe operating procedures and posting.
High Radiation Areas must either be locked
(as in the shielded installation) or be under
constant surveillance by the operator. The
perimeter of any Radiation Area created by
the system must be defined and posted.
According to ANSI N43.3, when the
radiation source is being approached
following the conclusion of a procedure, the
operator shall use a suitable calibrated and
operable survey instrument to verify that the
source is in its fully shielded condition or
that the X-ray tube has been turned off.
(Add facility-specific examples.)
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F. SUMMARY OF X-RAY DEVICES
The following table summarizes the classes of X-
ray devices recognized by ANSI. For the enclosed
beam, exempt shielded, and cabinet systems,
access is controlled by enclosing the X-rays
within a chamber or cabinet. The other systems
can have potentially hazardous dose rates outside
the system housing, so access must be controlled
by a combination of locked doors, posting, warning
lights, and procedures.
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SUMMARY OF X-RAY DEVICES
X-Ray Device
Category
Maximum Dose
Rate - Whole Body
Access
Enclosed beam
Analytical
0.25 mrem/hour
Fully enclosed
chamber
Open beam
Analytical
2.5 mrem/hour
Beam guard
Cabinet
Industrial
2.0 mrem/hour
Fully enclosed in a
cabinet
Exempt shielded
Industrial
0.5 mrem/hour
Enclosed
Shielded
Industrial
as posted
Locked doors
Unattended
Industrial
2 mrem/hour -
maximum 100
mrem/year
Secured access
panel
Open installation
Industrial
as posted
Constant
surveillance
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VII. MODULE 107 - RESPONSIBILITIES FOR X-RAY
SAFETY
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the
participants will understand who is
responsible for implementing X-ray safety
policies and procedures and what their
specific responsibilities are.
ii. Objectives.
Following self-study and/or classroom
review, the participants will be able to:
1. State the responsibilities of the X-
Ray Device Control Office.
2. State the responsibilities of
operating groups regarding X-ray
safety.
3. State the responsibilities of X-ray
device custodians.
4. State the responsibilities of X-ray
device operators.
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(Note: Module 107 is included as an
example. Insert facility-specific
information as appropriate.)
B. RESPONSIBILITIES
The responsibility for maintaining exposures from
X-rays ALARA is shared among the personnel
assigned to the X-Ray Device Control Office, the
operating groups, X-ray device custodians, and X-
ray device operators.
i. X-Ray Device Control Office.
The X-Ray Device Control Office is
responsible for:
Objective 8
1. Establishing requirements and
standards.
2. Offering consulting services and
training.
3. Approving purchases, moves,
transfers, and alterations of X-ray
equipment.
4. Surveying new equipment,
verifying that the appropriate
safety program requirements have
been met, and affixing compliance
labels to the devices.
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5. Issuing variances for devices that
do not meet one or more of the
requirements, if safety is achieved
through alternative means or if the
function could not be performed if
the device met the requirements.
ii. Operating Groups.
Operating groups are responsible for:
1. Complying with all X-ray safety
requirements.
2. Registering X-ray machines.
3. Preparing SOPs.
4. Appointing X-ray device
custodians.
5. Ensuring proper training of
operators.
iii. X-Ray Device Custodians
X-ray device custodians are responsible for
specific X-ray generating machines. Their
duties include:
1. Completing X-Ray-Generating
Device Registration forms and
submitting them to the X-Ray
Device Control Office to register
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new electron microscopes,
intentional X-ray devices, and new
X-ray tube assemblies or source
housings.
2. Making arrangements for operator
training.
3. Maintaining a list of qualified
operators authorized for particular
machines.
4. Documenting that operators have
read the appropriate SOPs and
machine safety features.
5. Posting an authorized operator list
near the control panel of each X-
ray device.
6. Checking enclosure door safety
interlocks every six months to
ensure proper functioning and
recording results on an interlock
test log posted on or near the
control panel.
7. Contacting the X-Ray Device
Control Office before performing
any repair, maintenance, and/or
nonroutine work that could cause
the exposure of any portion of the
body to the primary beam.
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8. Meeting all requirements of Safe
Operating Procedures, Special
Work Permits, and Lockout/
Tagout for Control of Hazardous
Energy Sources for Personnel
Safety (Red Lock Procedure).
iv. X-Ray Device Operators.
Authorized X-ray device operators are
responsible for knowing and following the
operator safety checklist, including:
1. Wearing a TLD badge.
2. Knowing the SOP for every
machine operated.
3. Notifying his/her supervisor of any
unsafe or hazardous work
situations.
4. Before reaching into the primary
beam, verifying that the beam
shutter is closed or that machine
power is off.
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5. Meeting all applicable training
requirements before operating
RPD.
6. Maintaining exposures ALARA.
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GLOSSARY
Absorbed dose: The energy absorbed by matter from ionizing radiation per unit mass of irradiated material
at the place of interest in that material. The absorbed dose is expressed in units of rad.
(10 CFR 835.2(b))
Accelerator: A device employing electrostatic or electromagnetic fields to impart kinetic energy to
molecular, atomic, or subatomic particles and capable of creating a radiological area (DOE Order 5480.25)
Examples include linear accelerators, cyclotrons, synchrotrons, synchrocyclotrons, free-electron lasers
(FELs), and ion LINACs. Single and tandem Van de Graaff generators, when used to accelerate charged
particles other than electrons, are also considered accelerators. Specifically excluded from this definition
(per DOE 0 5480.25) are the following:
• Unmodified commercially available units such as electron microscopes, ion implant devices, and X-ray
generators that are acceptable for industrial applications.
• Accelerator facilities not capable of creating a radiological area.
Access panel: Any barrier or panel that is designed to be removed or opened for maintenance or service
purposes, requires tools to open, and permits access to the interior of the cabinet. See also door, port, and
aperture.
Access port: See port.
Analytical X-ray device. A group of components that use intentionally produced X-rays to evaluate,
typically through X-ray diffraction or fluorescence, the phase state or elemental composition of materials.
Local components include those that are struck by X-rays such as the X-ray source housings, beam ports
and shutter assemblies, collimators, sample holders, cameras, goniometers, detectors, and shielding.
Remote components include power supplies, transformers, amplifiers, readout devices, and control panels.
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Anode: The positive electrode in an X-ray device that emits X-rays after being struck by energetic
electrons from the cathode.
Aperture: In this context, the opening within an X-ray source housing that permits the primary X-ray beam
to emerge in the intended direction. Such an aperture is not necessarily an open hole, but rather may be a
portion of the metal wall of the X-ray source housing that is significantly thinner than the surrounding X-ray
source housing walls.
Attenuation: The reduction of a radiation quantity upon passage of the radiation through matter, resulting
from all types of interaction with that matter. The radiation quantity may be, for example, the particle
fluency rate.
As low as reasonably achievable (ALARA): Means the approach to radiation protection to manage and
control exposures (both individual and collective) to the work force and to the general public to as low as is
reasonable, taking into account social, technical, economic, practical and public policy considerations.
ALARA is not a dose limit but a process which has the objective of attaining doses as far below the
applicable limits of 10 CFR 835 as is reasonably achievable. (10 CFR 835.2(a))
Bremsstrahlung: The electromagnetic radiation emitted when an electrically charged subatomic particle,
such as an electron, loses energy upon being accelerated and deflected by the electric field surrounding an
atomic nucleus. In German, the term means braking radiation.
Cabinet X-ray system: An industrial X-ray device with the X-ray tube installed in an enclosure (cabinet)
that, independent of existing architectural structures except the floor upon which it may be placed, is
intended to contain at least that portion of a material being irradiated, provide radiation attenuation, and
exclude individuals from its interior during X-ray generation. Included are all X-ray devices designed
primarily for the inspection of carry-on baggage at airline, railroad, and bus terminals. Excluded from this
definition are X-ray devices using a building wall for shielding and those using portable shields on a
temporary basis.
Cathode: The negative electrode that emits electrons in an X-ray device.
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Collimator: A device used to limit the size, shape, and direction of the primary beam.
Compliance label: A label affixed to an intentional X-ray device certifying that the device has been
surveyed and that safe operating requirements have been met.
Control panel: A device containing the means for regulating and activating X-ray equipment or for
preselecting and indicating operating factors.
Controlled Area: Any area to which access is managed to protect individuals from exposure to radiation
and/or radioactive material. (10 CFR 835.2(a))
Dark current: A current, usually of electrons, that may flow through an acceleration tube or wave guide
from sources other than the cathode of the accelerator. This is an abnormal phenomenon, often associated
with poor vacuum conditions or contaminated surfaces in the acceleration region.
Door: In this context, any barrier that is designed to be moved or opened for routine operation purposes,
does not require tools to open, and permits access to the interior of the cabinet.
Dose equivalent: The product of absorbed dose, a quality factor, and other modifying factors. The unit of
dose equivalent is the rem. (10 CFR 835.2 (b))
Dosimeter: A device that measures and indicates radiation dose.
Electron volt (eV): A unit of energy equal to the energy gained by an electron passing through a potential
difference of 1 volt.
Enclosed beam system: An analytical X-ray system in which all possible X-ray paths (primary as well as
diffracted beams) are fully enclosed.
Exempt shielded installation: An X-ray installation in which the source of radiation and all objects
exposed to that source are within a permanent enclosure that meets the requirements of a shielded
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installation and contains additional shielding such that the dose equivalent rate at any accessible area 2
inches (5 cm) from the outside surface of the enclosure shall not exceed 0.5 mrem in any 1 hour.
Exposure: A measure of the ionization produced in air by X-ray or gamma radiation defined up to 3 MeV.
It is the sum of the electrical charges of all of the ions of one sign produced in air when all electrons
liberated by photons in a volume element of air are completely stopped in the air, divided by the mass of the
air in the volume element. The unit of exposure is the roentgen (R) and is defined for photons with energy
up to 3 MeV.
External surface: An outside surface of a cabinet X-ray system, including the high-voltage generator,
doors, access panels, latches, control knobs, and other permanently mounted hardware, and including the
plane across any aperture or port.
Fail-safe design: A design in which the failure of any single component that can be realistically anticipated
results in a condition in which personnel are safe from exposure to radiation. Such a design should cause
beam-port shutters to close, primary transformer electrical power to be interrupted, or emergence of the
primary X-ray beam to be otherwise prevented upon failure of the safety or warning device.
Flash X-ray unit: A radiation-producing device that can produce nanosecond bursts of high-intensity X-
ray radiation.
Floor: In this context, the underside external surface of the cabinet.
Fluorescence analysis: Analysis of characteristic X-rays and the X-ray emission process.
Gauge: A device that produces ionizing radiation for the purpose of measuring particular properties of a
system.
Half-value layer (HVL): The thickness of a specified substance that, when introduced into a beam of
radiation, reduces the dose rate by one-half.
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High Radiation Area: Any area accessible to individuals in which radiation levels could result in an
individual receiving a deep dose equivalent in excess of 0.1 rem (0.001 sievert) in 1 hour at 30 centimeters
from the radiation source or from any surface that the radiation penetrates (10 CFR 835.2(a)).
Incidental X-ray device: A device that emits or produces X-rays in the process of its normal operation, in
which the X-rays are an unwanted byproduct of the device’s intended use. Examples include video display
terminals, electron microscopes, high-voltage electron guns, electron beam welders, ion implant devices,
microwave cavities used as beam guides, radio-frequency cavities, microwave generators
(magnetrons/klystrons), and field-emission electron beam diodes.
Installation: A radiation source, with its associated equipment, and the space in which it is located.
Installation enclosure: The portion of an X-ray installation that clearly defines the transition from a
noncontrolled to a controlled area and provides such shielding as may be required to limit the dose rate in
the noncontrolled area during normal operations.
Intentional X-ray device: A device in which electrons undergo acceleration in a vacuum and collide with
a metal anode target designed to produce X-rays for a particular application. Examples include diagnostic
medical/dental X-ray devices, electron LINACs used in radiation therapy applications, portable and fixed
flash X-ray systems, X-ray diffraction and fluorescence analysis equipment, cabinet X-ray systems, some
Van de Graaff generators, and electron LINACs.
Interlock: A device for precluding access to an area of radiation hazard either by preventing entry or by
automatically removing the hazard when the device is actuated.
Ion: An atom, or molecule bearing an electric charge, or an electron that is not associated with a nucleus.
Ionizing radiation: Any electromagnetic or particulate radiation capable of producing ions, directly or
indirectly, by interaction with matter, including gamma and X-rays and alpha, beta, and neutron particles.
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Lead equivalent: The thickness of lead affording the same attenuation, under specific conditions, as the
shielding material in use.
Leakage radiation: Any radiation, except the useful beam, coming from the X-ray assembly or sealed
source housing.
Medical X-ray system: An X-ray system for medical use, generally categorized as either diagnostic or
therapeutic. Diagnostic X-ray procedures are used to obtain images of body parts; therapeutic x-ray
procedures are used to manage malignancies.
Normal operation: Operation under conditions as recommended by the manufacturer of an X-ray system
or as specified by a written SOP. Recommended shielding and interlocks shall be in place and operable.
Occupancy factor: The factor by which the workload should be multiplied to correct for the degree or
type of occupancy of the area specified.
Open-beam system: An analytical X-ray system in which one or more X-ray paths (primary as well as
secondary) are not fully enclosed.
Open installation: An industrial X-ray installation that, because of operational requirements or temporary
needs, cannot be provided with the inherent degree of protection specified for other classes of industrial
installations. Generally mobile or portable equipment where fixed shielding cannot be effectively used.
Port: In this context, an opening on the outside surface of the cabinet that is designed to remain open
during X-ray production for the purpose of moving material to be irradiated into and out of the cabinet, or
for partial insertion of an object that will not fit inside the cabinet.
Primary beam: The X-radiation emitted directly from the target and passing through the window of the X-
ray tube.
Primary radiation: Radiation coming directly from the target of the X-ray tube or from the sealed source.
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Quality factor: An energy-dependent dimensionless factor by which absorbed dose is to be multiplied to
obtain, on a common scale for all ionizing radiations, the magnitude of radiation effects likely to be incurred
by exposed persons. The quality factor for X-rays, gamma rays, and most beta particles is 1.0.
Rad (radiation absorbed dose): The unit of absorbed dose. One rad equals 100 ergs per gram.
Radiation Area: Any area accessible to individuals in which radiation levels could result in an individual
receiving a deep dose equivalent in excess of 0.005 rem (0.05 millisievert) in 1 hour at 30 centimeters from
the source or from any surface that the radiation penetrates. (10 CFR 835.2(a)).
Radiation source: A device or a material that is capable of emitting ionizing radiation.
Radiological worker: A general employee whose job assignment involves operation of radiation-
producing devices or working with radioactive materials, or who is likely to be routinely occupationally
exposed above 0.1 rem per year total effective dose equivalent. (10 CFR 835.2(a))
Radiological control technician (RCT): Any person who is actively engaged in or who has completed
facility-specific RCT training and qualification programs.
Rem (roentgen equivalent man): The unit of dose equivalence used for humans, which considers the
biological effects of different types of radiation. The dose equivalent in rem is numerically equal to the
absorbed dose in rad multiplied by the applicable quality factor.
Roentgen (R): The unit of exposure. One roentgen equals 2.58 x 10-4 coulomb per kilogram of air.
Scattered radiation: Radiation that has been deviated in direction as a result of interaction with matter and
has usually been reduced in energy.
Secondary radiation: Radiation (electrons, X-rays, gamma rays, or neutrons) produced by the interaction
of primary radiation with matter.
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Shielding: Attenuating material used to reduce the transmission of radiation. The two general types of
shielding are primary and secondary. Primary shielding is material sufficient to attenuate the useful beam to
the required level. Secondary shielding is material sufficient to attenuate stray radiation to the required
level.
Shielded installation: An industrial X-ray installation in which the source of radiation and all objects
exposed to that source are within a permanent enclosure.
Skyshine: Radiation emerging from a shielded enclosure which then scatters off air molecules to increase
radiation levels at some distance from the outside of the shield.
Stem radiation: X-rays given off from parts of the anode other than the target, particularly from the target
support.
Stray radiation: Radiation other than the useful beam. It includes leakage and scattered radiation.
Survey: An evaluation of the radiological conditions and potential hazards incident to the production, use,
transfer, release, disposal, or presence of radioactive material or other sources of radiation. When
appropriate, such an evaluation includes a physical survey of the location of radioactive material and
measurements or calculations of levels of radiation, or concentrations or quantities of radioactive material
present. (10 CFR 835.2(a)).
System barrier: The portion of an X-ray installation that clearly defines the transition from a Controlled
Area to a Radiation Area and provides such shielding as may be required to limit the dose rate in the
Controlled Area during normal operation.
Tenth-value layer (TVL): The thickness of a specified substance that, when introduced into a beam of
radiation, reduces the dose rate to one-tenth of the original value. One TVL is equivalent to 3.3 HVLs.
Unattended installation: An industrial installation that consists of equipment designed and manufactured
for a specific purpose and that does not require personnel in attendance for its operation.
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Units: In accordance with 10 CFR 835.4, for all radiological units, the quantities used for records required
by 10 CFR 835 shall be the curie (Ci), rad or rem. SI units, Becquerel (Bq), gray (Gy), and sievert (Sv)
may be included parenthetically for reference to scientific standards, but are not authorized for required
records. To convert conventional radiation units to SI units, the following factors are used:
1 rad = 0.01 gray (Gy)
1 rem = 0.01 sievert (Sv)
1 Ci = 3.7 X 1010 Bq
Use factor: The fraction of the workload during which the useful beam is pointed in the direction under
consideration.
Useful beam: The part of the primary and secondary radiation that passes through the aperture, cone, or
other device used for collimation.
Very High Radiation Area: Any area accessible to individuals in which radiation levels could result in an
individual receiving an absorbed dose in excess of 500 rads (5 grays) in 1 hour at 1 meter from a radiation
source or from any surface that the radiation penetrates (10 CFR 835.2(a)).
Warning label: A label affixed to the X-ray device that provides precautions and special conditions of use.
Workload: A measure, in suitable units, of the amount of use of radiation equipment. For the purpose of
this standard, the workload is expressed in milliampere-minutes per week for X-ray sources and in
roentgens per week at 1 meter from the source for gamma-ray sources and high-energy equipment (such as
linear accelerators, betatrons, etc.).
X-ray accessory apparatus: Any portion of an X-ray installation that is external to the radiation source
housing and into which an X-ray beam is directed for making X-ray measurements or for other uses.
X-Ray Device Control Office: A team that establishes X-ray device program requirements and standards,
provides X-ray device radiation protection consultation, and serves as the central point of contact for the
management/control of X-ray devices. This function may have a facility-specific name.
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X-ray device custodian: A person designated by line management as responsible for specific X-ray
devices. This individual is responsible for designating the operators of specific X-ray devices, arranging for
the operators to attend X-ray safety training, assisting in the development and maintenance of the X-ray
device SOP, familiarizing operators with the X-ray device SOP, maintaining records of operator training
and safety interlock checks, serving as the point of contact for the line organization's X-ray devices, and
coordinating surveys with the X-Ray Device Control Office. An X-ray device custodian may also be an
X-ray device operator.
X-ray device operator: An individual designated in writing by the X-ray-device custodian and qualified
by training and experience to operate a specific X-ray device.
X-ray diffraction: The scattering of X-rays by matter with accompanying variation in intensity in different
directions due to interference effects.
X-ray installation: One or more X-ray systems, the surrounding room or controlled area, and the
installation enclosure.
X-ray power supply: The portion of an X-ray device that generates the accelerating voltage and current
for the X-ray tube.
X-ray source housing: An enclosure directly surrounding an X-ray tube that provides attenuation of the
radiation emitted by the X-ray tube. The X-ray source housing typically has an aperture through which the
useful beam is transmitted.
X-ray system: An assemblage of components for the controlled generation of X-rays.
X-ray tube: An electron tube that is designed for the conversion of electrical energy to X-ray energy.
X-ray tube assembly: An array of components typically including the cathode, anode, X-ray target, and
electron-accelerating components within a vacuum.
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Student’s Guide
Radiological Safety Training
for Radiation-Producing (X-Ray) Devices
Coordinated and Conducted
for
Office of Environment, Safety & Health
U.S. Department of Energy
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Course Developers
Jim Allan Stanford Linear Accelerator Center
Ken Barat Lawrence Berkeley National Laboratory
Rocky Barnum Pacific Northwest National Laboratories
Brooke Buddemeier Lawrence Livermore National Laboratory
Richard Cooke Argonne National Laboratory - East
Ted DeCastro Lawrence Berkeley National Laboratory
William Egbert Lawrence Livermore National Laboratory
Darrel Howe Westinghouse Savannah River Company
David Lee Los Alamos National Laboratory
Kathleen McIntyre Brookhaven National Laboratory
Mike McNaughten Los Alamos National Laboratory
Edward Schultz Sandia National Laboratories
Brian Thomson Sandia National Laboratories
Paula Trinoskey Lawrence Livermore National Laboratory
Susan Vosburg Sandia National Laboratories
Ann Anthony Los Alamos National Laboratory
Course Reviewers
Peter O'Connell U.S. Department of Energy
Randy Sullivan ATL International
Technical Standard Managers U.S. Department of Energy
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Table of Contents
Page
TERMINAL OBJECTIVE ................................................................................................................ 1 ENABLING OBJECTIVES .............................................................................................................. 1
I. MODULE 101 - RADIATION PROTECTION PRINCIPLES......................................................... 2
A. OBJECTIVES ....................................................................................................................... 2 B. ATOMS................................................................................................................................. 2 C. IONIZATION ...................................................................................................................... 3 D. RADIATION......................................................................................................................... 3 E. UNITS................................................................................................................................... 3 F. BACKGROUND RADIATION............................................................................................ 4 G. DOSE LIMITS ...................................................................................................................... 4 H. CAUSES OF ACCIDENTAL EXPOSURES (KEY ITEM)................................................. 6 I. ALARA................................................................................................................................. 6 J. REDUCING EXTERNAL DOSE (KEY ITEM) .................................................................. 7
II. MODULE 102 - PRODUCTION OF X-RAYS ................................................................................ 8
A. OBJECTIVES ....................................................................................................................... 8 B. ELECTROMAGNETIC RADIATION................................................................................. 9 C. X-RAY PRODUCTION...................................................................................................... 11 D. EFFECT OF VOLTAGE AND CURRENT ON PHOTON ENERGY AND POWER...... 12 E. INTERACTION WITH MATTER ..................................................................................... 13
III. MODULE 103 - BIOLOGICAL EFFECTS.................................................................................... 17
A. OBJECTIVES ..................................................................................................................... 17 B. EARLY HISTORY OF X-RAYS ....................................................................................... 17 C. BIOLOGICAL EFFECTS OF IONIZATION..................................................................... 19 D. FACTORS THAT DETERMINE BIOLOGICAL EFFECTS ............................................ 19 E. SOMATIC EFFECTS ......................................................................................................... 22 F. HERITABLE EFFECTS.................................................................................................... 26
IV. MODULE 104 - RADIATION DETECTION ................................................................................ 27
A. OBJECTIVES ..................................................................................................................... 27 B. RADIATION SURVEYS.................................................................................................... 27 C. X-RAY DETECTION INSTRUMENTS ............................................................................ 27 D. PERSONNEL-MONITORING DEVICES ......................................................................... 29
V. MODULE 105 - PROTECTIVE MEASURES ............................................................................... 31
A. OBJECTIVES ..................................................................................................................... 31 B. RADIOLOGICAL CONTROLS......................................................................................... 31 C. RADIOLOGICAL POSTINGS........................................................................................... 32 D. INTERLOCKS.................................................................................................................... 36 E. SHIELDING........................................................................................................................ 36 F. WARNING DEVICES........................................................................................................ 38 G. WORK DOCUMENTS....................................................................................................... 39
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VI. MODULE 106 - X-RAY GENERATING DEVICES..................................................................... 42
A. OBJECTIVES ..................................................................................................................... 42 B. INCIDENTAL AND INTENTIONAL DEVICES.............................................................. 42 C. INCIDENTAL X-RAY DEVICES ..................................................................................... 43 D. INTENTIONAL ANALYTICAL X-RAY DEVICES ........................................................ 44 E. INTENTIONAL INDUSTRIAL X-RAY DEVICES .......................................................... 46 F. SUMMARY OF X-RAY DEVICES................................................................................... 49
VII. MODULE 107 - RESPONSIBILITIES FOR X-RAY SAFETY..................................................... 50
A. OBJECTIVES ..................................................................................................................... 50 B. RESPONSIBILITIES.......................................................................................................... 50
GLOSSARY................................................................................................................................................. 54
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TERMINAL OBJECTIVE:
Demonstrate a basic understanding of :
C General radiation protection principles for safe operation of X-ray devices.
ENABLING OBJECTIVES:
When the participants have completed this course, the participants will be able to:
EO1 Describe ionizing radiation.
EO2 Describe what X-rays are, how they are generated, and how they interact with matter.
EO3 Describe the biological effects of X-rays.
EO4 Identify and describe radiation-monitoring instruments and personnel-monitoring devices
appropriate for detecting X-rays.
EO5 Demonstrate a familiarity with DOE dose limits, facility-specific administrative controls,
ALARA, and the major methods for controlling and minimizing external exposure.
EO6 Identify and describe protective measures that restrict or control access to X-ray areas and
devices, and warn of X-ray hazards; and be able to identify and describe work documents
that provide specific procedures to ensure safe operation of X-ray devices.
EO7 Identify and describe the categories of X-ray-producing devices.
EO8 Explain who is responsible for implementing X-ray safety policies and procedures and
describe their specific responsibilities.
EO9 Identify causes of accidental exposures.
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I. MODULE 101 - RADIATION PROTECTION PRINCIPLES
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the participants should understand basic radiation
protection principles essential to the safe operation of X-ray devices.
ii. Objectives.
Following self-study and/or classroom review, the participants will be able to:
1. Define ionizing radiation.
2. Identify sources of natural and manmade background radiation.
3. Define the DOE dose limits and facility-specific administrative control levels.
4. Describe the ALARA principle.
5. List the three major methods by which external exposure is reduced.
B. ATOMS
The atom, the basic unit of matter, is made up of three primary particles: protons, neutrons, and
electrons. Protons and neutrons are found in the nucleus of the atom; electrons are found
orbiting the nucleus. Protons have a positive charge; neutrons are neutral; electrons have a
negative charge. The configuration of electron shells and the number of electrons in the shells
determine the chemical properties of atoms.
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C. IONIZATION
An atom usually has a number of electrons equal to the number of protons in its nucleus so that
the atom is electrically neutral. A charged atom, called an ion, can have a positive or negative
charge. Free electrons also are called ions. An ion is formed when ionizing radiation interacts
with an orbiting electron and causes it to be ejected from its orbit, a process called ionization.
This leaves a positively charged atom (or molecule) and a free electron.
D. RADIATION
Radiation as used here means alpha particles, beta particles, gamma rays, X-rays, neutrons,
high-speed electrons, high-speed protons, and other particles capable of producing ions.
Radiation with enough energy to cause ionization is referred to as ionizing radiation. Radiation
that lacks the energy to cause ionization is referred to as non-ionizing radiation. Examples of
non-ionizing radiation include radio waves, microwaves, and visible light.
For radiation-protection purposes, ionization is important because it affects chemical and
biological processes and allows the detection of radiation.
For most radiation-protection situations, ionizing radiation takes the form of alpha, beta, and
neutron particles, and gamma and X-ray photons.
X-rays and gamma rays are a form of electromagnetic radiation. X-rays differ from gamma rays
in their point of origin. Gamma rays originate from within the atomic nucleus, whereas X-rays
originate from the electrons outside the nucleus and from free electrons decelerating in the
vicinity of atoms (i.e., bremsstrahlung). Module 102 discusses how X-rays are produced.
E. UNITS
• Roentgen (R), a measure of radiation exposure, is defined by ionization in air.
• Rad, a measure of the energy absorbed per unit mass. It is defined for any absorbing
material.
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• Rem, a unit of dose equivalent, which is the energy absorbed per unit mass times the
applicable quality factor and other modifying factors.
For X-rays, it may be assumed that 1 R = 1 rad = 1 rem = 1000 mrem.
F. BACKGROUND RADIATION
Background radiation, to which everyone is exposed, comes from both natural and manmade
sources. Natural background radiation can be categorized as cosmic and terrestrial. Radon is
the major contributor to terrestrial background. The most common sources of manmade
background radiation are medical procedures and consumer products.
The average background dose to the general population from both natural and manmade
sources is about 350 mrem per year to the whole body. Naturally occurring sources contribute
an average of 200 mrem per year from radon daughters, about 40 mrem per year from internal
emitters such as potassium-40, about 30 mrem per year from cosmic and cosmogenic sources,
and about 30 mrem per year from terrestrial sources such as naturally occurring uranium and
thorium. Manmade sources contribute an average of about 50 mrem per year to the whole body
from medical procedures such as chest X-rays.
The deep dose equivalent from a chest X-ray is 5 - 10 mrem, a dental X-ray is 50 - 300 mrem,
and mammography is 0.5 - 2 rem.
G. DOSE LIMITS
Limits on occupational doses are based on data on the biological effects of ionizing radiation.
The International Commission on Radiological Protection and the National Council on
Radiation Protection and Measurements publish guidance for setting radiation protection
standards. The DOE, Nuclear Regulatory Commission, and Environmental Protection Agency
set regulatory requirements related to radiation protection. These limits are set to minimize the
likelihood of biological effects.
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The following table lists both DOE dose limits and administrative control levels. Refer to:
10 CFR 835.202-208
DOE Dose Limits and Facility-Specific Administrative Control Levels
DOE
Dose Limits
Facility-Specific Administrative
Control Levels
whole body
Total Effective Dose
Equivalent
5 rem/year
insert facility-specific value
extremity
50 rem/year
insert facility-specific value
skin
50 rem/year
insert facility-specific value
internal organ
committed dose
equivalent
50 rem/year
insert facility-specific value
lens of the eye
15 rem/year
insert facility-specific value
embryo/fetus
0.5 rem/term of pregnancy
(for the embryo/fetus of workers
who declare pregnancy)
insert facility-specific value
minors and public
0.1 rem/year
insert facility-specific value
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DOE facilities are designed and operated to reduce personnel dose equivalents as far below the
occupational limits as reasonably achievable. The dose equivalent received by DOE X-ray
workers is typically between 0 and 100 mrem per year above the natural background.
H. CAUSES OF ACCIDENTAL EXPOSURES (KEY ITEM)
Although most X-ray workers do not receive radiation doses near the regulatory limit, it is
important to recognize that X-ray device-related accidents have occurred when proper
procedures have not been followed. Failure to follow proper procedures has been the result of:
• Rushing to complete a job.
• Boredom.
• Fatigue.
• Illness.
• Personal problems.
• Lack of communication.
• Complacency.
Every year there are numerous X-ray incidents nationwide. Of these, about one third result in
injury to a person. The incident rate at DOE laboratories is much lower than the national
average.
I. ALARA
Because the effects of chronic doses of low levels of ionizing radiation are not precisely known,
we assume there is some risk for any dose. The ALARA principle is to keep radiation dose as
low as reasonably achievable, considering economic and social constraints.
The goal of an ALARA Program is to keep radiation dose as far below the occupational dose
limits and administrative control levels as is reasonably achievable. The success of an ALARA
Program is directly linked to a clear understanding and following of the policies and procedures
for the protection of workers. Keeping radiation dose ALARA is the responsibility of all
workers, management, and the radiation-protection organization.
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J. REDUCING EXTERNAL DOSE (KEY ITEM)
Three basic ways to reduce external doses are to
• Minimize time.
• Maximize distance.
• Use shielding.
Minimize time near a source of radiation by planning ahead. Increase distance by moving away
from the source of radiation whenever possible. The dose from X-ray sources is inversely
proportional to the square of the distance. This is called Athe inverse square law,@ that is,
when the distance is doubled, the dose is reduced to one-fourth of the original value. Proper
facility design uses the amount and type of shielding appropriate for the radiation hazard.
Lead, concrete, and steel are effective in shielding against X-rays.
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II. MODULE 102 - PRODUCTION OF X-RAYS
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the participants should understand what X-rays are and
how they are produced so that the participants will be able to work around them safely.
ii. Objectives.
Following self-study and/or classroom review, the participants will be able to:
1. Define the types of electromagnetic radiation.
2. Describe the difference between X-rays and gamma rays.
3. Identify how X-rays are produced.
4. Define bremsstrahlung and characteristic X-rays.
5. Describe how X-ray tube voltage and current affect photon energy and power.
6. Explain how X-rays interact with matter.
7. Identify how energy relates to radiation dose.
8. Discuss the effects of voltage, current, and filtration on X-rays.
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B. ELECTROMAGNETIC RADIATION
i. Types of Electromagnetic Radiation.
X-rays are a type of electromagnetic radiation. Other types of electromagnetic radiation
are radio waves, microwaves, infrared, visible light, ultraviolet, and gamma rays. The
types of radiation are distinguished by the amount of energy carried by the individual
photons.
All electromagnetic radiation consists of photons, which are individual packets of energy.
For example, a household light bulb emits about 1021 photons of light (non-ionizing
radiation) per second.
The energy carried by individual photons, which is measured in electron volts (eV), is
related to the frequency of the radiation. Different types of electromagnetic radiation and
their typical photon energies are listed in the following table.
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Electromagnetic Radiation
Type
Typical Photon Energy
Typical Wavelengths
radio wave
1 ueV
1 m
microwave
1 meV
1 mm (10-3m)
infrared
1 eV
1 um (10-6m)
red light
2 eV
6000 Angstrom (10-10m)
violet light
3 eV
4000 Angstrom
ultraviolet
4 eV
3000 Angstrom
X-ray
100 keV
0.1 Angstrom
gamma ray
1 MeV
0.01 Angstrom
ii. X-Rays and Gamma Rays.
X-rays and gamma rays both ionize atoms. The energy required for ionization varies with
material (e.g., 34 eV in air, 25 eV in tissue) but is generally in the range of several eV. A
100 keV X-ray can potentially create thousands of ions.
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As discussed in Module 101, the distinction between X-rays and gamma rays is their origin,
or method of production. Gamma rays originate from within the nucleus; X-rays originate
from atomic electrons and from free electrons decelerating in the vicinity of atoms (i.e.,
bremsstrahlung).
In addition, gamma photons often have more energy than X-ray photons. For example,
diagnostic X-rays are about 40 keV, whereas gammas from cobalt-60 are over 1 MeV.
However, there are many exceptions. For example, gammas from technicium-99m are 140
keV, and the energy of X-rays from a high-energy radiographic machine may be as high as
10 MeV.
C. X-RAY PRODUCTION
Radiation-producing devices produce X-rays by accelerating electrons through an electrical
voltage potential and stopping them in a target. Many devices that use a high voltage and a
source of electrons produce X-rays as an unwanted byproduct of device operation. These are
called incidental X-rays.
Most X-ray devices emit electrons from a cathode, accelerate them with a voltage, and allow
them to hit an anode, which emits X-ray photons.
i. Bremsstrahlung.
When electrons hit the anode, they decelerate or brake emitting bremsstrahlung (meaning
braking radiation in German). Bremsstrahlung is produced most effectively when small
charged particles interact with large atoms such as when electrons hit a tungsten anode.
However, bremsstrahlung can be produced with any charged particles and any target. For
example, at research laboratories, bremsstrahlung has been produced by accelerating
protons and allowing them to hit hydrogen.
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ii. Characteristic X-Rays.
When electrons change from one atomic orbit to another, characteristic X-rays are
produced. The individual photon energies are characteristic of the type of atom and can be
used to identify very small quantities of a particular element. For this reason, they are
important in analytical X-ray applications at research laboratories.
D. EFFECT OF VOLTAGE AND CURRENT ON PHOTON ENERGY AND POWER
It is important to distinguish between the energy of individual photons in an X-ray beam and
the total energy of all the photons in the beam. It is also important to distinguish between
average power and peak power in a pulsed X-ray device.
Typically, the individual photon energy is given in electron volts (eV), whereas the power of a
beam is given in watts (W). An individual 100 keV photon has more energy than an individual
10 keV photon. However, an X-ray beam consists of a spectrum (a distribution) of photon
energies and the rate at which energy is delivered by a beam is determined by the number of
photons of each energy. If there are many more low energy photons, it is possible for the low
energy component to deliver more energy.
The photon energy distribution may be varied by changing the voltage. The number of photons
emitted may be varied by changing the current.
i. Voltage.
The power supplies for many X-ray devices do not produce a constant potential (D.C.) high
voltage but instead energize the X-ray tube with a time varying or pulsating high voltage.
In addition, since the bremsstrahlung X-rays produced are a spectrum of energies up to a
maximum equal to the electron accelerating maximum voltage, the accelerating voltage of
the X-ray device is often described in terms of the peak kilovoltage or kVp.
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A voltage of 50 kVp will produce a spectrum of X-ray energies with the theoretical
maximum being 50 keV. The spectrum of energies is continuous from the maximum to
zero. However, X-ray beams are typically filtered to minimize the low-energy component.
Low-energy X-rays are not useful in radiography, but can deliver a significant dose.
Many X-ray devices have meters to measure voltage. Whenever the voltage is on, a device
can produce some X-rays, even if the current is too low to read.
ii. Current.
The total number of photons produced by an X-ray device depends on the current, which is
measured in amperes, or amps (A). The current is controlled by increasing or decreasing
the number of electrons emitted from the cathode. The higher the electron current, the
more X-ray photons are emitted from the anode. Many X-ray devices have meters to
measure current. However, as mentioned above, X-rays can be produced by voltage even if
the current is too low to read on the meter. This is sometimes called dark current. This
situation can cause unnecessary exposure and should be addressed in SOPs or work
documents.
iii. Determining Electrical Power.
Power, which is measured in watts (W), equals voltage times current (P = V x I). For
example, a 10 kVp device with a current of 1 mA uses 10 W of power.
(Insert facility-specific examples for determining electrical power.)
E. INTERACTION WITH MATTER
i. Scattering.
When X-rays pass through any material, some will be transmitted, some will be absorbed,
and some will scatter. The proportions depend on the photon energy, the type of material
and its thickness.
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X-rays can scatter off a target to the surrounding area, off a wall and into an adjacent room,
and over and around shielding. A common mistake is to install thick shielding walls
around an X-ray source but ignore the roof; X-rays can scatter off air molecules over
shielding walls to create a radiation field known as skyshine. The emanation of X-rays
through and around penetrations in shielding walls is called radiation streaming.
ii. Implications of Power and X-Ray Production.
When high-speed electrons strike the anode target, most of their energy is converted to heat
in the target, but a portion is radiated away as X-rays. As stated previously, the electrical
power of an electrical circuit is given by:
P = V x I
P is the power in watts or joules/second, V is the potential difference in volts, and I is the
current in amps.
The power developed in the anode of an X-ray tube can be calculated using this
relationship. Consider a 150 kilovolt (kVp) machine, with a current of 50 milliamps (mA).
P = [150,000 (V)] [0.050 (I)] = 7500 W.
This is about the same heat load as would be found in the heating element of an electric
stove. This power is delivered over a very short period of time, typically less than 1
second. More powerful X-ray machines use higher voltages and currents and may develop
power as high as 50,000 W or more. Cooling the anode is a problem that must be
addressed in the design of X-ray machines. Tungsten is used because of its high melting
temperature, and copper is used because of its excellent thermal conductivity. These
elements may be used together, with a tungsten anode being embedded in a large piece of
copper.
The percentage of the power transformed to X-rays can be estimated by the following
relationship:
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Fraction of incident electron energy transformed into X-ray energy equals:
(7 X 10 -4) x Z x E
Where Z is the atomic number of the element (74 for tungsten) and E is the maximum
energy of the incoming electrons in MeV.
In this case, the fraction would be:
(7 X 10 -4) x 74 x 0.150 = 0.008
In the above example P is 7500 W. So the electron energy incident upon the anode is:
7500 W = 7500 J/s
Then the energy transformed into X-rays would be 0.008 [7500] = 60 J/s.
1 J = 107 ergs, and 100 ergs/g = 1 rad.
So this X-ray energy represents:
6.0 x 108 ergs/sec.
If all this X-ray energy were deposited in 1 g of tissue, the dose would be:
6.0 x 108 ergs/sec [1 rad/100ergs/g] =
6.0 x 106 rad/sec.
However, in practical applications X-ray beams are filtered to remove softer X-rays not
useful in radiology, the X-ray pulse is much less than 1 second, and the useful beam region
is several cm away from the anode target. These design features lower the dose rates of the
useful X-ray beam significantly. The dose rate in a typical X-ray beam is estimated in
Module 103 section E iii.
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iii. Filtration.
Low- and high-energy photons are sometimes referred to as soft and hard X-rays,
respectively. Because hard X-rays are more penetrating, they are more desirable for
radiography (producing a photograph of the interior of the body or a piece of apparatus).
Soft X-rays are less useful for radiography because they are largely absorbed near the
surface of the body being X-rayed. However, there are medical applications where soft X-
rays are useful.
A filter, such as a few millimeters of aluminum, or copper may be used to harden the beam
by absorbing most of the low-energy photons. The remaining photons are more penetrating
and are more useful for radiography.
In X-ray analytical work (X-ray diffraction and fluorescence), filters with energy selective
absorption edges are not used to harden the beam, but to obtain a more monochromatic
beam (a beam with predominantly one energy). By choosing the right element, it is
possible to absorb a band of high-energy photons preferentially over an adjacent band of
low energy photons.
(Insert facility-specific examples of filtration.)
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III. MODULE 103 - BIOLOGICAL EFFECTS
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the participants should understand the biological effects of
X-rays and the importance of protective measures for working with or around X-rays.
ii. Objectives.
Following self-study and/or classroom review, the participants will be able to:
1. Outline the early history of X-rays and the consequences of working with or around
X-rays without protective measures.
2. Identify factors that determine the biological effects of X-ray exposure.
3. State the differences between thermal and X-ray burns.
4. Identify the signs and symptoms of an acute dose from X-rays.
5. Explain the effects of chronic exposure to X-rays.
6. Identify the difference between somatic and heritable effects.
B. EARLY HISTORY OF X-RAYS
i. Discovery of X-Rays.
X-rays were discovered in 1895 by German scientist Wilhelm Roentgen. On November 8,
1895, Roentgen was investigating high-voltage electricity and noticed that a nearby
phosphor glowed in the dark whenever he switched on the apparatus. He quickly
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demonstrated that these unknown “x” rays, as he called them, traveled in straight lines,
penetrated some materials, and were stopped by denser materials. He continued
experiments with these “x” rays and eventually produced an X-ray picture of his wife's
hand showing the bones and her wedding ring. On January 1, 1896, Roentgen mailed
copies of this picture along with his report to fellow scientists.
By early February 1896, the first diagnostic X-ray in the United States was taken, followed
quickly by the first X-ray picture of a fetus in utero. By March of that year, the first dental
X-rays were taken. In that same month, French scientist Henri Becquerel was looking for
fluorescence effects from the sun, using uranium on a photographic plate. The weather
turned cloudy so he put the uranium and the photographic plate into a drawer. When
Becquerel developed the plates a few weeks later, he realized he had made a new
discovery. His student, Marie Curie, named it radioactivity.
ii. Discovery of Harmful Effects.
Because virtually no protective measures were used in those early days, it was not long
after the discovery of X-rays before people began to learn about their harmful effects. X-
ray workers were exposed to very large doses of radiation, and skin damage from that
exposure was observed and documented early in 1896. In March of that year, Thomas
Edison reported eye injuries from working with X-rays. By June, experimenters were
being cautioned not to get too close to X-ray tubes. By the end of that year, reports were
being circulated about cases of hair loss, reddened skin, skin sloughing off, and lesions.
Some X-ray workers lost fingers, and some eventually contracted cancer. By the early
1900s, the potential carcinogenic effect of X-ray exposure in humans had been reported.
Since that time, more than a billion dollars has been spent in this country alone on research
investigating the biological effects of ionizing radiation. National and international
agencies have formed to aid in the standardization of the uses of X-rays to ensure safer
practices.
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C. BIOLOGICAL EFFECTS OF IONIZATION
X-rays can penetrate into the human body and ionize atoms. This process creates radicals that
can break or modify chemical bonds within critical biological molecules. This can cause cell
injury, cell death, and may be the cause of radiation-induced cancer. The biological effect of
radiation depends on several factors (discussed below) including the dose and dose rate.
In some cases, altered cells are able to repair the damage. However, in other cases, the effects
are passed to daughter cells through cell division and after several divisions can result in a
group of cells with altered characteristics. These cells may result in tumor or cancer
development. If enough cells in a body organ are injured or altered, the functioning of the
organ can be impaired.
D. FACTORS THAT DETERMINE BIOLOGICAL EFFECTS
Several factors contribute to the biological effects of X-ray exposure, including:
• Dose rate.
• Total dose received.
• Energy of the radiation.
• Area of the body exposed.
• Individual sensitivity.
• Cell sensitivity.
i. Dose Rate.
The rate of dose delivery is commonly categorized as acute or chronic. An acute dose is
received in a short period (seconds to days); a chronic dose is received over a longer period
(months to years).
For the same total dose, an acute dose is more damaging than a chronic dose. It is believed
that this effect is due to the ability of cells to repair damage over time. With an acute dose,
a cell may receive many “hits” without sufficient time to repair damage.
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ii. Total Dose Received.
The higher the total amount of radiation received, the greater the biological effects. The
effects of a whole body dose of less than 25 rem are generally not clinically observable.
For doses of 25-100 rem there are generally no symptoms, but a few persons may exhibit
mild prodromal symptoms, such as nausea and anorexia. Bone-marrow damage may be
noted, and a decrease in red and white blood-cell counts and platelet count should be
discernable. 100-300 rem may result in mild to severe nausea, malaise, anorexia, and
infection. Hematologic damage will be more severe. Recovery is probable, though not
assured.
Although effects of lower doses have not been observed directly, it is conservatively
assumed that the higher the total dose, the greater the risk of contracting fatal cancer
without consideration of a threshold for effects. This conservative assumption is
sometimes called the “linear no threshold” relationship of health effects to dose.
iii. Energy of the Radiation.
The energy of X-rays can vary from less than 1 keV up to more than 10 MeV. The higher
the energy of the X-ray, the more penetrating it will be into body tissue.
Lower energy X-rays are largely absorbed in the skin. They can cause a significant skin
dose but may contribute little dose to the whole body (depending on energy).
iv. Area of the Body Exposed.
Just as a burn to a large portion of the body is more damaging than a burn confined to a
smaller area, so also is a radiation dose to the whole body more damaging than a dose to
only a small area. In addition, the larger the area, the more difficult it is for the body to
repair the damage.
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v. Individual Sensitivity.
Some individuals are more sensitive to radiation than others. Age, gender, and overall
health can have an effect on how the body responds to radiation exposure.
vi. Cell Sensitivity.
Some cells are more sensitive to radiation than others. Cells that are more sensitive to
radiation are radiosensitive; cells that are less sensitive to radiation are radioresistant.
The law of Bergonie and Tribondeau states: The radiosensitivity of a tissue is directly
proportional to its reproductive capacity and inversely proportional to its degree of
differentiation.
It is generally accepted that cells tend to be radiosensitive if they are:
1) Cells that have a high division rate
2) Cells that have a high metabolic rate
3) Cells that are of a non-specialized type
4) Cells that are well nourished
The following are radiosensitive tissues:
1) Germinal
2) Hematopoietic
3) Epithelium of the skin
4) Epithelium of the gastrointestinal tract
The following are radioresistant tissues:
1) Bone
2) Liver
3) Kidney
4) Cartilage
5) Muscle
6) Nervous system tissue
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E. SOMATIC EFFECTS
Somatic effects are biological effects that occur in the individual exposed to radiation. Somatic
effects may result from acute or chronic doses of radiation.
i. Early Acute Somatic Effects.
The most common injury associated with the operation of X-ray analysis equipment occurs
when a part of the body, usually a hand, is exposed to the primary X-ray beam. Both X-ray
diffraction and fluorescence analysis equipment generate high-intensity, low-energy X-rays
that can cause severe and permanent injury if any part of the body is exposed to the primary
beam.
The most common injury associated with the operation of industrial X-ray equipment
occurs when an operator is exposed to the primary X-ray beam for as little as a few
seconds.
These types of injuries are sometimes referred to as radiation burns.
ii. Difference Between X-Ray Damage and Thermal Burns (Key Item).
Most nerve endings are near the surface of the skin, so they give immediate warning of heat
or a surface thermal burn such as the participants might receive from touching a high-
temperature object. In contrast, the body can not immediately feel exposure to X-rays.
X-ray damage has historically been referred to as a radiation “burn,” perhaps because the
reaction of the skin after the radiation exposure may appear similar to a thermal burn. In
fact, X-ray damage to the tissue is very different from a thermal burn and there is no
sensation or feeling as the damage is occurring.
In radiation burns, the radiation does not harm the outer, mature, nondividing skin layers.
Rather, most of the X-rays penetrate to the deeper, basal skin layer, damaging or killing the
rapidly dividing germinal cells that are otherwise destined to replace the outer layers that
slough off. Following this damage, as the outer cells are naturally sloughed off, they are
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not replaced. Lack of a fully viable basal layer of cells means that X-ray burns are slow to
heal, and in some cases may never heal. Frequently, such burns require skin grafts. In
some cases, severe X-ray burns have resulted in gangrene and amputation.
An important variable is the energy of the radiation because this determines the depth of
penetration in a given material. Heat radiation is infrared, typically 1 eV; sunburn is
caused by ultraviolet rays, typically 4 eV; and X-rays are typically 10 - 100 keV, which are
capable of penetrating to the depth of the basal layer of the skin.
iii. Early Signs and Symptoms of Accidental Exposure to X-Rays.
Note: the doses discussed in this section are localized shallow skin doses and/or localized
doses, but not whole body doses. Whole body deep doses of this magnitude would likely
be fatal. Accidental exposures from RPDs are generally localized to a small part of the
body.
~600 rad. An acute dose of about 600 rad to a part of the body causes a radiation burn
equivalent to a first-degree thermal burn or mild sunburn. Typically there is no immediate
pain that would cause the participants to pull away, but a sensation of warmth or itching
occurs within a few hours after exposure. An initial reddening or inflammation of the
affected area usually appears several hours after exposure and fades after a few more hours
or days. The reddening may reappear as late as two to three weeks after the exposure. A
dry scaling or peeling of the irradiated portion of the skin is likely to follow.
If the participants have been working with or around an X-ray device and the participants
notice an unexplained reddening of the skin, notify the supervisor and the Occupational
Medicine Group. Aside from avoiding further injury and guarding against infection,
further medical treatment will probably not be required and recovery should be fairly
complete.
An acute dose of 600 rad delivered to the lens of the eye causes a cataract to begin to form.
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~1,000 rad. An acute dose of about 1,000 rad to a part of the body causes serious tissue
damage similar to a second-degree thermal burn. First reddening and inflammation occur,
followed by swelling and tenderness. Blisters will form within one to three weeks and will
break open, leaving raw painful wounds that can become infected. Hands exposed to such
a dose become stiff, and finger motion is often painful. If the participants develop
symptoms such as these, seek immediate medical attention to avoid infection and relieve
pain.
~2,000 rad. An acute dose of about 2,000 rad to a part of the body causes severe tissue
damage similar to a scalding or chemical burn. Intense pain and swelling occur within
hours. For this type of radiation burn, seek immediate medical treatment to reduce pain.
The injury may not heal without surgical removal of exposed tissue and skin grafting to
cover the wound. Damage to blood vessels also occurs.
~3,000 rad. An acute dose of 3,000 rad to a part of the body completely destroys tissue
and surgical removal is necessary.
It does not take long to get a significant dose from an X-ray unit. The dose rate from an X-
ray unit can be estimated from the Health Physics and Radiological Health Handbook,
1992 edition Table 10.1.1.
Example: Assume:
2.5 mm Al filter
100 kVp
100 mA
1 sec exposure
30 cm distance
Dose estimate (in air, assuming electron equilibrium): 12.8 Rad
(Compare these values to facility-specific equipment or examples.)
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iv. Latent Effects from Radiation Exposure.
The probability of a latent effect appearing several years after radiation exposure depends
on the amount of the dose. The higher the dose, the greater the risk of developing a health
effect. When an individual receives a large accidental exposure and the prompt effects of
that exposure have been dealt with, there still remains a concern about latent effects years
after the exposure. Although there is no unique disease associated with exposure to
radiation, there is a possibility of developing fatal cancer. The higher the accumulated
dose, the greater is the risk of health effect, based on the linear-no threshold model.
v. Risk of Developing Cancer from Low Doses.
It is not possible to absolutely quantify the risk of cancer from low doses of radiation
because the health effects cannot be distinguished from the relatively large natural cancer
rate (approximately 20 percent of Americans die from cancer). The risk of health effects
from low doses must be inferred from effects observed from high acute doses. The risk
estimates for high doses were developed through studies of Japanese atomic bomb
survivors, uranium miners, radium watch-dial painters, and radiotherapy patients. These
risk factors are applied to low doses with a reduction factor for chronic exposures.
However, below 10 rem, health effects are too small to measure. The dose limits and
administrative control levels listed in Module 101 have been established so that the risk to
workers is on a par with the risks to workers in safe industries, assuming a linear
relationship between dose and health effects. However, these are maximum values and the
ALARA principle stresses maintaining doses well below these values.
vi. Effects of Prenatal Exposure (Teratogenic Effects).
The embryo/fetus is especially sensitive to radiation. The embryo is sensitive to radiation
because of the relatively high replication activity of the cells and the large number of
nonspecialized cells.
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Workers who become pregnant are encouraged to declare their pregnancy in writing to their
supervisors. The dose limit for the embryo/fetus of a declared pregnant worker is 500
mrem during the term of the pregnancy; 10 CFR 835.206 (b) states “Substantial variation
above a uniform exposure rate that would satisfy the limits provided in 10 CFR835.206 (a)
[i.e., 500 mrem for term of pregnancy] shall be avoided.”
F. HERITABLE EFFECTS
Heritable effects are biological effects that are inherited by children from their parents at
conception. Irradiation of the reproductive organs can damage cells that contain heritable
information passed on to offspring.
Radiation-induced hereditary effects have been observed in large-scale experiments with fruit
flies and mice irradiated with large doses of radiation. Such health effects have not been
observed in humans. Based on the animal data, however, the conservative assumption is made
that radiation-induced hereditary effects could occur in humans.
Radiation-induced heritable effects do not result in genetic diseases that are uniquely different
from those that occur naturally. Extensive observations of the children of Japanese atomic
bomb survivors have not revealed any statistically significant hereditary health effects.
Note: Congenital (teratogenic) effects are not heritable effects. Congenital effects are not
inherited; they are caused by the action of agents such as drugs, alcohol, radiation, or
infection to an unborn child in utero. Congenital or teratogenic effects did occur in children
who were irradiated in utero by the atomic bombs at Hiroshima or Nagasaki.
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IV. MODULE 104 - RADIATION DETECTION
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the participants should understand which radiation-
monitoring instruments and which personnel-monitoring devices are appropriate for
detecting X-rays.
ii. Objectives.
Following self-study and/or classroom review, the participants will be able to:
1. Identify the instruments used for X-ray detection and
2. Identify the devices used for personnel monitoring.
B. RADIATION SURVEYS
Radiation protection surveys should be conducted on all new or newly installed X-ray devices
by the X-Ray Device Control Office (or facility-specific equivalent) and repeated at a
frequency determined by site policies.
C. X-RAY DETECTION INSTRUMENTS
External exposure controls used to minimize the dose equivalent to workers are based on the
data taken with portable radiation-monitoring instruments during a radiation survey. An
understanding of these instruments is important to ensure that the data obtained are accurate
and appropriate for the source of radiation.
Many factors can affect how well the survey measurement reflects the actual conditions,
including:
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• Selection of the appropriate instrument based on type and energy of radiation and on
radiation intensity.
• Correct operation of the instrument based on the instrument operating characteristics and
limitations.
• Calibration of the instrument to a known radiation field similar in type, energy, and
intensity to the radiation field to be measured.
i. Instruments Used for X-Ray Detection
It is important to distinguish between detection and measurement of X-rays. Equipment
users often use a detector to detect the presence of X-rays, for example, to verify that the
device is off before entry into the area. The measurement of X-rays is normally the job of a
qualified Radiological Control Technician.
Measurement of radiation dose rates and surveys of record require an instrument that reads
roentgen or rem (R/hour, mR/hour, rem/hour, mrem/hour) rather than counts per minute
(cpm) or disintegrations per minute (dpm). Ion chambers measure energy deposited and
are good instruments for measuring X-ray radiation dose levels.
Instruments such as Geiger-Mueller (GM) counters are effective for detection of radiation
because of their good sensitivity. However, because both low-energy and high-energy
photons discharge the counter, GM counters do not quantify a dose well. A thin-window
GM counter is the instrument of choice for the detection of X-rays. However, this is not
the instrument of choice for measurement of X-ray dose.
ii. Facility-Specific Instrumentation
(Insert facility-specific information on instrumentation, as appropriate.)
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D. PERSONNEL-MONITORING DEVICES
Note: X-ray leakage from RPD housings or shielding may be a narrow beam that is difficult to
detect and may not be recorded by personnel monitoring devices.
i. Whole Body Dosimeters.
Operators of intentional X-ray devices usually wear dosimetry such as thermoluminescent
dosimeters (TLDs) film or badges. These dosimeters can accurately measure radiation
doses as low as 10 mrem and are used to determine the dose of record. However, they must
be sent to a processor to be read. Therefore, the exposed individual may not be aware of
his exposure until the results have been reported (typically 1 day - several weeks).
There are several precautions that are important in the use of dosimeters. Dosimeters
should be worn in a location that will record a dose representative of the trunk of the body.
Standard practice is to wear a dosimeter between the neck and the waist, but in specific
situations such as nonuniform radiation fields, special considerations may apply. Some
dosimeters have a required orientation with a specific side facing out.
(Insert facility-specific information on dosimetry, as appropriate.)
ii. Extremity Dosimeters.
Finger-ring and wrist dosimeters may be used to assess radiation dose to the hands.
(Insert facility-specific information on dosimetry, as appropriate.)
iii. Pocket Dosimeters.
Pocket ionization chambers, such as pencil dosimeters or electronic dosimeters, are used in
radiological work. In contrast to TLDs, they give an immediate readout of the radiation
dose. Pencil dosimeters are manufactured with scales in several different ranges, but the
0B500 mR range, marked in increments of 20 mR, is often used. The dose is read by
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observing the position of a hairline that moves upscale in proportion to dose. Pocket
dosimeters are supplemental and used primarily as radiological worker management tools.
They are not typically used for determining the dose of record required by 10 CFR 835.
iv. Alarming Dosimeters.
In higher dose-rate areas, an alarming dosimeter may be used to provide an audible warning
of radiation. This contributes to keeping doses ALARA by increasing a worker's awareness
of the radiation.
Specific applications may require special considerations. For example, low-energy X-rays
will not penetrate the walls of some dosimeters. Flash X-ray devices produce a very short
pulse that is not correctly measured by most dose-rate instruments.
(Insert facility-specific information as appropriate.)
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V. MODULE 105 - PROTECTIVE MEASURES
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the participants should understand protective measures that
restrict or control access to X-ray areas and devices or warn of X-ray hazards, and should
be able to use work documents that provide specific procedures to ensure safe operation of
X-ray devices.
ii. Objectives.
Following self-study and/or classroom review, the participants will be able to:
1. Identify and state specific administrative and engineered controls.
2. Identify and state specific radiological postings.
3. Define “interlocks”, as applicable.
4. Explain specific shielding practices.
5. Identify typical RPD warning devices.
6. Outline site-specific work documents.
B. RADIOLOGICAL CONTROLS
To control exposure to radiation, as well as maintain exposure ALARA, access to radiological
areas is restricted by a combination of administrative and engineering controls.
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Examples of administrative controls include:
• Posting.
• Warning signals and labels.
• Work control documents such as SOPs and RWPs.
Examples of engineered controls include:
• Interlocks.
• Shielding.
For high-radiation areas where radiation levels exist such that an individual could exceed a
deep dose equivalent of 1 rem in any 1 hour at 30 cm from the source or surface that the
radiation penetrates, one or more of the following features shall be used to control exposure:
• A control device that prevents entry.
• A device that prevents use of the radiation source while personnel are present.
• A device that energizes a visible and audible alarm.
• Locked entry ways.
• Continuous direct or electronic surveillance to prevent unauthorized entry.
• A device that generates audible and visual alarms in sufficient time to permit evacuation.
In addition to the above measures, for very high radiation areas ( areas accessible to individuals
in which radiation levels could result in an individual receiving a dose in excess of 500 rads in
1 hour), additional measures shall be implemented to ensure individuals are not able to gain
access.
C. RADIOLOGICAL POSTINGS
i. Purpose of Posting.
The two primary reasons for radiological posting are:
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1. To inform workers of the radiological conditions and
2. To inform workers of the entry requirements for an area.
ii. General Posting Requirements.
1. Signs contain the standard radiation symbol colored magenta or black on a yellow
background.
2. Signs shall be clearly and conspicuously posted to alert personnel to the presence
of radiation. Signs may also include radiological protection instructions.
3. If more than one radiological condition exists in the same area, each condition
should be identified.
4. Rope, tape, chain, or similar barrier material used to designate radiological areas
should be yellow and magenta.
5. Physical barriers should be placed so that they are clearly visible from all
accessible directions and at various elevations.
6. Posting of doors should be such that the postings remain visible when doors are
open or closed.
7. Radiological postings that indicate an intermittent radiological condition should
include a statement specifying when the condition exists, such as
“CAUTION, RADIATION AREA WHEN RED LIGHT IS ON.”
For a Radiation Area, wording on the posting shall include the words:
“CAUTION, RADIATION AREA.”
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For a High Radiation Area, wording on the posting shall include the words:
“DANGER, HIGH RADIATION AREA.”
For a Very High Radiation Area, wording on the posting shall include the words:
“GRAVE DANGER, VERY HIGH RADIATION AREA.”
The same posting requirements apply for X-ray or gamma radiation as for any
other type of radiation. Areas controlled for radiological purposes are posted
according to the radiation dose rates in the area, as shown in the following table.
These definitions are standard throughout the DOE complex.
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Areas
Defining Condition
Controlled Area
Means any area to which access is managed to
protect individuals from exposure to radiation
and/or radioactive material.
Radiation Area
Means any area accessible to individuals in
which radiation levels could result in an
individual receiving a deep dose equivalent in
excess of 0.005 rem (0.05 millisievert) in 1 hour
at 30 centimeters from the source or from any
surface that the radiation penetrates.
High Radiation Area
Means any area accessible to individuals, in
which radiation levels could result in an
individual receiving a deep dose equivalent in
excess of 0.1 rem (0.001 sievert) in 1 hour at 30
centimeters from the radiation source or from
any surface that the radiation penetrates.
Very High Radiation Area
Means any area accessible to individuals in
which radiation levels could result in an
individual receiving an absorbed dose in excess
of 500 rads (5 grays) in 1 hour at 1 meter from a
radiation source or from any surface that the
radiation penetrates.
(Insert facility-specific information on posting, labeling, and entry requirements, as applicable.)
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D. INTERLOCKS
Fail-safe interlocks should be provided on doors and access panels of X-ray devices so that X-
ray production is not possible when they are open. A fail-safe interlock is designed so that any
failure that can reasonably be anticipated will result in a condition in which personnel are safe
from excessive radiation exposure.
Guidance from the ANSI standards is that interlocks should be tested by the operating group at
least every six months. The interlock test procedure may be locally specified, but typically is as
follows:
• Energize the X-ray tube.
• Open each door or access panel one at a time.
• Observe the X-ray warning light or current meter at the control panel.
• Record the results in a log.
(Insert facility-specific information, as appropriate.)
E. SHIELDING
i. Analytical Systems.
For analytical X-ray machines, such as X-ray fluorescence and diffraction systems, the
manufacturer provides shielding in accordance with ANSI N43.2. However, prudent
practice requires that any device or source that involves radiation should be surveyed to
determine the adequacy of the shielding.
Enclosed beam systems have sufficient shielding so that the dose rate at 5 cm from its
outer surface does not exceed 0.25 mrem per hour under normal operating conditions.
The dose rate may be difficult to evaluate. According to ANSI N43.2, this requirement is
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met if the shielding is at least equal to the thickness of lead specified in the following
table for the maximum rated anode current and potential.
MINIMUM SHIELDING TO KEEP THE DOSE RATE BELOW 0.25 MREM/HOUR
ANODE CURRENT
MILLIMETERS OF LEAD
(MA)
50 KVP
70 KVP
100 KVP
20
1.5
5.6
7.7
40
1.6
5.8
7.9
80
1.6
5.9
--
160
1.7
--
--
ii. Industrial Systems.
Some industrial X-ray systems, such as the cabinet X-ray systems used for airport
security, are completely enclosed in an interlocked and shielded cabinet. Larger systems
such as medical X-ray units are enclosed in a shielded room to which access is restricted.
Shielding for X-ray rooms is conservatively designed to handle the expected workload
conditions. Radiological control technicians (RCTs) periodically verify that the shielding
integrity has not deteriorated.
X-Ray Device Control Office (or facility-specific equivalent) personnel develop
recommendations for shielding based on the following information:
1. Shielding the primary X-ray beam and
2. Shielding the areas not in the line of the primary beam from leakage and scattered
radiation.
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There are independent analyses for each component to derive an acceptable shield
thickness.
For example, the calculation used for the primary X-ray beam depends on:
- Peak voltage.
- The maximum permissible exposure rate to an individual.
- The workload of the machine expressed in mA min/wk.
- The use factor: the fraction of the workload during which the useful
beam is pointed in a direction under consideration.
- The occupancy factor that takes into account the fraction of time that
an area outside the barrier is likely to be occupied by a given
individual.
- The distance from the target of the tube to the location under
consideration.
The calculation uses conservative values and derives a value (K) that is used with
graphs to determine shield thickness of a given type of material (e.g., lead or
concrete).
F. WARNING DEVICES
Operators should be aware of the status of the X-ray tube. Indicators that warn of X-ray
production typically include:
§ A current meter on the X-ray control panel.
§ A warning light labeled X-RAYS ON near or on the control panel.
§ Warning light labeled X-RAYS ON near any X-ray room door.
These warning lights or indicators are activated automatically when power is available for
X-ray production.
For X-ray systems with an open beam in a shielded room, evacuation warning signals and
signs must be activated at least 20 seconds before X-ray production can be started. Any
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person who is inside the room when warning signals come on should immediately leave
the room and activate the panic or scram switch on the way out. This is an emergency
system designed to shut down the X-ray system immediately.
(Insert facility-specific information.)
G. WORK DOCUMENTS
(Note: this section is provided only as an example and should be replaced with facility-
specific information.)
i. Typical Standard Operating Procedures (SOP).
An X-ray device has a procedure such as an SOP to promote safe and efficient
operation. SOPs typically include the following:
1. Description/specification of the X-ray device and the purpose for which it
is used.
2. Normal X-ray parameters (peak power, current, exposure time, X-ray
source-to-film distance, etc.).
3. Procedures for proper sample preparation, alignment procedures, or
handling of object to be radiographed.
4. Description of all safety hazards (electrical, mechanical, explosive, as
well as radiation hazards) associated with the operation of the X-ray
device.
5. Description of the safety features such as interlocks and warning signals
and any other safety precautions.
6. Procedures for performing interlock tests and the recommended frequency
of such tests.
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7. Required operator training and dosimetry.
8. Posting of signs and labels.
9. X-ray device safety checklist (items to be checked periodically or each
day before use).
10. Actions to take in the event of an abnormal occurrence or emergency.
11. Requirements for the use of a radiation-monitoring instrument upon entry
into the Radiation Area to verify that the X-ray beam is off are specified
in ANSI N43.3 for some industrial X-ray devices.
X-Ray Device Control Office personnel (or facility-specific equivalent) review
each SOP to verify that it establishes appropriate safety practices and they can
assist the operating groups in preparing or modifying an SOP. The current SOP
should be kept near the X-ray device.
Operating groups are responsible for ensuring that the operator becomes familiar
with and uses the SOP. The operator is responsible for following the SOP.
ii. Radiological Work Permits (RWPs).
RWPs are used to establish radiological controls for entry into radiological areas.
They serve to:
1. Inform workers of area radiological conditions.
2. Inform workers of entry requirements into the areas.
3. Provide a means to relate radiation doses to specific work activities.
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A job-specific RWP is used to control nonroutine operations or work areas with
changing radiological conditions.
RWPs are typically used in conjunction with X-ray devices when any of the
following situations exist:
1. A compliance label for a newly acquired X-ray device cannot be issued
because the SOP for that device has not yet been written and approved.
2. A portable X-ray device or open system used only for a short period that
does not warrant writing an SOP.
3. An event that requires an operator enter the area when the X-ray beam is
on.
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VI. MODULE 106 - X-RAY GENERATING DEVICES
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the participants should understand the categories of
X-ray producing devices and the hazards associated with each.
(Note: Module 106 reflects the guidance of the ANSI Standards N43.2 and N43.3.
Insert facility-specific information as appropriate.)
ii. Objectives.
Following self-study and/or review, the participants will be able to:
1. Contrast incidental and intentional X-ray devices.
2. Contrast analytical and industrial X-ray devices.
3. Identify open and enclosed beam installations.
4. Describe the safety features essential for operation of industrial and
analytical systems.
B. INCIDENTAL AND INTENTIONAL DEVICES
X-ray systems are divided into two broad categories: intentional and incidental.
An incidental X-ray device produces X-rays that are not wanted or used as a part of the
designed purpose of the machine. Shielding of an incidental X-ray device should preclude
significant exposure. Examples of incidental systems are computer monitors, televisions,
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electron microscopes, high-voltage electron guns, electron beam welding machines,
electrostatic separators, and Jennings switches.
An intentional X-ray device is designed to generate an X-ray beam for a particular use.
Examples include X-ray diffraction and fluorescence analysis systems, flash X-ray
systems, medical X-ray machines, and industrial cabinet and noncabinet X-ray equipment.
Intentional X-ray devices are further divided into two subcategories: analytical and
industrial.
ANSI has issued two standards that provide radiation safety guidelines for X-ray systems.
ANSI N43.2 applies to non-medical X-ray systems and ANSI N43.3 applies to X-ray
diffraction and fluorescence systems.
C. INCIDENTAL X-RAY DEVICES
i. Exempt Shielded Systems.
Exempt shielded systems are defined in the ANSI Standard N43.3. Electron
microscopes and other systems that are exempt shielded are inherently safe, and
require review only on purchase or modification. The exposure rate during any
phase of operation of these devices at the maximum-rated continuous beam current
for the maximum-rated accelerating potential should not exceed 0.5 mrem/hour at
2 inches (5 cm) from any accessible external surface.
(Add facility-specific examples.)
ii. Other Devices.
At a research laboratory, many devices produce incidental X-rays. Any device that
combines high voltage and a vacuum could, in principle, produce X-rays. For
example, a television or computer monitor generates incidental X-rays, but in
modern designs the intensity is small, much less than 0.5 mrem/hour.
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Occasionally, this hazard is recognized only after the device has operated for some
time. If the participants suspect an X-ray hazard, contact an RCT or the X-Ray
Device Control Office (or facility-specific equivalent) to survey the device.
(Add facility-specific examples.)
D. INTENTIONAL ANALYTICAL X-RAY DEVICES
i. Analytical X-Ray Devices.
Analytical X-ray devices use X-rays for diffraction or fluorescence experiments.
These research tools are normally used in materials science. ANSI N43.2 defines
two types of analytical X-ray systems: enclosed beam and open beam.
The following safety features are common to both systems:
1. A fail-safe light or indicator is installed in a conspicuous location near the
X-ray tube housing. These indicators are energized automatically and
only when the tube current flows or high voltage is applied to the X-ray
tube.
2. Accessories to the equipment have a beam stop or other barrier.
3. Shielding is provided.
(Add facility-specific examples.)
ii. Enclosed-Beam System.
In an enclosed-beam system, all possible X-ray paths (primary and diffracted) are
completely enclosed so that no part of a human body can be exposed to the beam
during normal operation. Because it is safer, the enclosed-beam system should be
selected over the open-beam system whenever possible.
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The following safety features are specified by ANSI N43.2 for an enclosed-beam
X-ray system:
1. The sample chamber door or other enclosure should have a fail-safe
interlock on the X-ray tube high-voltage supply or a shutter in the primary
beam so that no X-ray beam can enter the sample chamber while it is
open.
2. X-ray tube, sample, detector, and analyzing crystal (if used) must be
enclosed in a chamber or coupled chambers that cannot be entered by any
part of the body during normal operation.
3. Radiation leakage measured at 2 inches (5 cm) from any outer surface
must not exceed 0.25 mrem/hour during normal operation.
(Add facility-specific examples.)
iii. Open-Beam System.
According to ANSI N43.2, a device that does not meet the enclosed-beam
standards is classified as an open-beam system. In an open-beam system, one or
more X-ray beams are not enclosed, making exposure of human body parts
possible during normal operation. The open-beam system is acceptable for use
only if an enclosed beam is impractical because of any of the following reasons:
1. A need for frequent changes of attachments and configurations.
2. A need for making adjustments with the X-ray beam energized.
3. Motion of specimen and detector over wide angular limits.
4. The examination of large or bulky samples.
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The following safety features are essential in an open-beam X-ray system:
1. Each port of the X-ray tube housing must have a beam shutter.
2. All shutters must have a conspicuous SHUTTER OPEN indicator of fail-
safe design.
3. Shutters at unused ports should be mechanically or electrically secured to
prevent casual opening.
4. Special rules apply when the accessory setup is subject to change as is the
case with powder diffraction cameras. In these cases, the beam shutter
must be interlocked so the port will be open only when the accessory is in
place.
5. Exposure rates adjacent to the system must not exceed 2.5 mrem/hour at
5cm from the surface of the housing.
6. A guard or interlock must prevent entry of any part of the body into the
primary beam.
(Insert facility-specific information if system definitions differ from the above.)
E. INTENTIONAL INDUSTRIAL X-RAY DEVICES
i. Industrial X-Ray Devices.
Industrial X-ray devices are used for radiography, for example, to take pictures of
the inside of an object as in an X-ray of a pipe weld or to measure the thickness of
material. ANSI standard N43.3 defines five classes of industrial X-ray
installations: cabinet, exempt shielded, shielded, unattended, and open.
(Add facility-specific examples.)
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ii. Cabinet X-ray Installation.
A cabinet X-ray installation is similar in principle to the analytical enclosed beam
system. The X-ray tube is installed in an enclosure (cabinet) that contains the
object being irradiated, provides shielding, and excludes individuals from its
interior during X-ray generation. A common example is the X-ray device used to
inspect carry-on baggage at airline terminals. Certified cabinet X-ray systems
comply with the regulations of 21 CFR 1020.40. Exposure rates adjacent to a
cabinet X-ray system shall not exceed 2 mrem/hour.
(Add facility-specific examples.)
iii. Exempt Shielded Installation.
An exempt shielded facility or installation is similar to a cabinet X-ray installation.
It provides a high degree of inherent safety because the protection depends on
passive shielding and not on compliance with procedures. This type does not
require restrictions in occupancy since passive shielding is sufficient. The low
allowable dose equivalent rate of 0.5 mrem in any 1 hour 5 cm from the accessible
surface of the enclosure for this class of installation necessitates a high degree of
installed shielding surrounding the X-ray device.
(Add facility-specific examples.)
iv. Shielded Installation.
A shielded installation has less shielding than exempt shielded. This is a cost
advantage for fixed installations, particularly for high-energy sources where the
reduction in shielding may result in significant savings. However, there is more
reliance on protective measures such as warning lights, posting, and procedures.
However, the posting and access control requirements, of 10 CFR 835 apply. Any
High Radiation Area must be appropriately controlled and any Radiation Area
must be defined and posted.
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(Add facility-specific examples.)
v. Unattended Installation.
An unattended installation consists of equipment designed and manufactured for a
specific purpose and does not require personnel in attendance for its operation.
Steps must be taken to ensure that the dose to personnel is less than 100
mrem/year. However, a short term limit of 2 mrem/hour may be used provided the
expected dose to personnel is less than 100 mrem/year.
(Add facility-specific examples.)
vi. Open Installation
An open installation has X-ray paths that are not enclosed. An example would be a
portable X-ray machine outdoors in an emergency response situation, with the X-
ray tube not enclosed inside a shielded room. This class is acceptable for use only
if operational requirements prevent the use of one of the other classes. Its use is
limited mainly to mobile and portable equipment where fixed shielding cannot be
used. The protection of personnel and the public depends almost entirely on strict
adherence to safe operating procedures and posting. High Radiation Areas must
either be locked (as in the shielded installation) or be under constant surveillance
by the operator. The perimeter of any Radiation Area created by the system must
be defined and posted.
According to ANSI N43.3, when the radiation source is being approached
following the conclusion of a procedure, the operator shall use a suitable calibrated
and operable survey instrument to verify that the source is in its fully shielded
condition or that the X-ray tube has been turned off.
(Add facility-specific examples.)
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F. SUMMARY OF X-RAY DEVICES
The following table summarizes the classes of X-ray devices recognized by ANSI. For
the enclosed beam, exempt shielded, and cabinet systems, access is controlled by
enclosing the X-rays within a chamber or cabinet. The other systems can have potentially
hazardous dose rates outside the system housing, so access must be controlled by a
combination of locked doors, posting, warning lights, and procedures.
SUMMARY OF X-RAY DEVICES
X-Ray Device
Category
Maximum Dose
Rate - Whole Body
Access
Enclosed beam
Analytical
0.25 mrem/hour
Fully enclosed
chamber
Open beam
Analytical
2.5 mrem/hour
Beam guard
Cabinet
Industrial
2.0 mrem/hour
Fully enclosed in a
cabinet
Exempt shielded
Industrial
0.5 mrem/hour
Enclosed
Shielded
Industrial
as posted
Locked doors
Unattended
Industrial
2 mrem/hour -
maximum 100
mrem/year
Secured access
panel
Open installation
Industrial
as posted
Constant
surveillance
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VII. MODULE 107 - RESPONSIBILITIES FOR X-RAY SAFETY
A. OBJECTIVES
i. Module Objective.
Upon completion of this unit, the participants will understand who is responsible
for implementing X-ray safety policies and procedures and what their specific
responsibilities are.
ii. Objectives.
Following self-study and/or classroom review, the participants will be able to:
1. State the responsibilities of the X-Ray Device Control Office.
2. State the responsibilities of operating groups regarding X-ray safety.
3. State the responsibilities of X-ray device custodians.
4. State the responsibilities of X-ray device operators.
(Note: Module 107 is included as an example. Insert facility-specific information
as appropriate.)
B. RESPONSIBILITIES
The responsibility for maintaining exposures from X-rays ALARA is shared among the
personnel assigned to the X-Ray Device Control Office, the operating groups, X-ray
device custodians, and X-ray device operators.
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i. X-Ray Device Control Office.
The X-Ray Device Control Office is responsible for:
1. Establishing requirements and standards.
2. Offering consulting services and training.
3. Approving purchases, moves, transfers, and alterations of X-ray
equipment.
4. Surveying new equipment, verifying that the appropriate safety program
requirements have been met, and affixing compliance labels to the
devices.
5. Issuing variances for devices that do not meet one or more of the
requirements, if safety is achieved through alternative means or if the
function could not be performed if the device met the requirements.
ii. Operating Groups.
Operating groups are responsible for:
1. Complying with all X-ray safety requirements.
2. Registering X-ray machines.
3. Preparing SOPs.
4. Appointing X-ray device custodians.
5. Ensuring proper training of operators.
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iii. X-Ray Device Custodians
X-ray device custodians are responsible for specific X-ray generating machines.
Their duties include:
1. Completing X-Ray-Generating Device Registration forms and submitting
them to the X-Ray Device Control Office to register new electron
microscopes, intentional X-ray devices, and new X-ray tube assemblies or
source housings.
2. Making arrangements for operator training.
3. Maintaining a list of qualified operators authorized for particular
machines.
4. Documenting that operators have read the appropriate SOPs and machine
safety features.
5. Posting an authorized operator list near the control panel of each X-ray
device.
6. Checking enclosure door safety interlocks every six months to ensure
proper functioning and recording results on an interlock test log posted on
or near the control panel.
7. Contacting the X-Ray Device Control Office before performing any
repair, maintenance, and/or nonroutine work that could cause the
exposure of any portion of the body to the primary beam.
8. Meeting all requirements of Safe Operating Procedures, Special Work
Permits, and Lockout/Tagout for Control of Hazardous Energy Sources
for Personnel Safety (Red Lock Procedure).
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iv. X-Ray Device Operators.
Authorized X-ray device operators are responsible for knowing and following the
operator safety checklist, including:
1. Wearing a TLD badge.
2. Knowing the SOP for every machine operated.
3. Notifying his/her supervisor of any unsafe or hazardous work situations.
4. Before reaching into the primary beam, verifying that the beam shutter is
closed or that machine power is off.
5. Meeting all applicable training requirements before operating RPD.
6. Maintaining exposures ALARA.
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GLOSSARY
Absorbed dose: The energy absorbed by matter from ionizing radiation per unit mass of irradiated material
at the place of interest in that material. The absorbed dose is expressed in units of rad.
(10 CFR 835.2(b)).
Accelerator: A device employing electrostatic or electromagnetic fields to impart kinetic energy to
molecular, atomic, or subatomic particles and capable of creating a radiological area (DOE Order 5480.25).
Examples include linear accelerators, cyclotrons, synchrotrons, synchrocyclotrons, free-electron lasers
(FELs), and ion LINACs. Single and tandem Van de Graaff generators, when used to accelerate charged
particles other than electrons, are also considered accelerators. Specifically excluded from this definition
(per DOE 0 5480.25) are the following:
• Unmodified commercially available units such as electron microscopes, ion implant devices, and X-
ray generators that are acceptable for industrial applications.
• Accelerator facilities not capable of creating a radiological area.
Access panel: Any barrier or panel that is designed to be removed or opened for maintenance or service
purposes, requires tools to open, and permits access to the interior of the cabinet. See also door, port, and
aperture.
Access port: See port.
Analytical X-ray device. A group of components that use intentionally produced X-rays to evaluate,
typically through X-ray diffraction or fluorescence, the phase state or elemental composition of materials.
Local components include those that are struck by X-rays such as the X-ray source housings, beam ports
and shutter assemblies, collimators, sample holders, cameras, goniometers, detectors, and shielding.
Remote components include power supplies, transformers, amplifiers, readout devices, and control panels.
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Anode: The positive electrode in an X-ray device that emits X-rays after being struck by energetic
electrons from the cathode.
Aperture: In this context, the opening within an X-ray source housing that permits the primary X-ray beam
to emerge in the intended direction. Such an aperture is not necessarily an open hole, but rather may be a
portion of the metal wall of the X-ray source housing that is significantly thinner than the surrounding X-ray
source housing walls.
Attenuation: The reduction of a radiation quantity upon passage of the radiation through matter, resulting
from all types of interaction with that matter. The radiation quantity may be, for example, the particle
fluency rate.
As low as reasonably achievable (ALARA): Means the approach to radiation protection to manage and
control exposures (both individual and collective) to the work force and to the general public to as low as is
reasonable, taking into account social, technical, economic, practical and public policy considerations.
ALARA is not a dose limit but a process which has the objective of attaining doses as far below the
applicable limits of 10 CFR 835 as is reasonably achievable. (10 CFR 835.2(a))
Bremsstrahlung: The electromagnetic radiation emitted when an electrically charged subatomic particle,
such as an electron, loses energy upon being accelerated and deflected by the electric field surrounding an
atomic nucleus. In German, the term means braking radiation.
Cabinet X-ray system: An industrial X-ray device with the X-ray tube installed in an enclosure (cabinet)
that, independent of existing architectural structures except the floor upon which it may be placed, is
intended to contain at least that portion of a material being irradiated, provide radiation attenuation, and
exclude individuals from its interior during X-ray generation. Included are all X-ray devices designed
primarily for the inspection of carry-on baggage at airline, railroad, and bus terminals. Excluded from this
definition are X-ray devices using a building wall for shielding and those using portable shields on a
temporary basis.
Cathode: The negative electrode that emits electrons in an X-ray device.
Collimator: A device used to limit the size, shape, and direction of the primary beam.
GLOSSARY (continued)
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Compliance label: A label affixed to an intentional X-ray device certifying that the device has been
surveyed and that safe operating requirements have been met.
Control panel: A device containing the means for regulating and activating X-ray equipment or for
preselecting and indicating operating factors.
Controlled Area: Any area to which access is managed to protect individuals from exposure to radiation
and/or radioactive material. (10 CFR 835.2(a))
Dark current: A current, usually of electrons, that may flow through an acceleration tube or wave guide
from sources other than the cathode of the accelerator. This is an abnormal phenomenon, often associated
with poor vacuum conditions or contaminated surfaces in the acceleration region.
Door: In this context, any barrier that is designed to be moved or opened for routine operation purposes,
does not require tools to open, and permits access to the interior of the cabinet.
Dose equivalent: The product of absorbed dose, a quality factor, and other modifying factors. The unit of
dose equivalent is the rem. (10 CFR 835.2 (b))
Dosimeter: A device that measures and indicates radiation dose.
Electron volt (eV): A unit of energy equal to the energy gained by an electron passing through a potential
difference of 1 volt.
Enclosed beam system: An analytical X-ray system in which all possible X-ray paths (primary as well as
diffracted beams) are fully enclosed.
Exempt shielded installation: An X-ray installation in which the source of radiation and all objects
exposed to that source are within a permanent enclosure that meets the requirements of a shielded
installation and contains additional shielding such that the dose equivalent rate at any accessible area 2
inches (5 cm) from the outside surface of the enclosure shall not exceed 0.5 mrem in any 1 hour.
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Exposure: A measure of the ionization produced in air by X-ray or gamma radiation defined up to 3 MeV.
It is the sum of the electrical charges of all of the ions of one sign produced in air when all electrons
liberated by photons in a volume element of air are completely stopped in the air, divided by the mass of the
air in the volume element. The unit of exposure is the roentgen (R) and is defined for photons with energy
up to 3 MeV.
External surface: An outside surface of a cabinet X-ray system, including the high-voltage generator,
doors, access panels, latches, control knobs, and other permanently mounted hardware, and including the
plane across any aperture or port.
Fail-safe design: A design in which the failure of any single component that can be realistically anticipated
results in a condition in which personnel are safe from exposure to radiation. Such a design should cause
beam-port shutters to close, primary transformer electrical power to be interrupted, or emergence of the
primary X-ray beam to be otherwise prevented upon failure of the safety or warning device.
Flash X-ray unit: A radiation-producing device that can produce nanosecond bursts of high-intensity X-
ray radiation.
Floor: In this context, the underside external surface of the cabinet.
Fluorescence analysis: Analysis of characteristic X-rays and the X-ray emission process.
Gauge: A device that produces ionizing radiation for the purpose of measuring particular properties of a
system.
Half-value layer (HVL): The thickness of a specified substance that, when introduced into a beam of
radiation, reduces the dose rate by one-half.
High Radiation Area: Any area accessible to individuals in which radiation levels could result in an
individual receiving a deep dose equivalent in excess of 0.1 rem (0.001 sievert) in 1 hour at 30 centimeters
from the radiation source or from any surface that the radiation penetrates (10 CFR 835.2(a)).
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Incidental X-ray device: A device that emits or produces X-rays in the process of its normal operation, in
which the X-rays are an unwanted byproduct of the device’s intended use. Examples include video display
terminals, electron microscopes, high-voltage electron guns, electron beam welders, ion implant devices,
microwave cavities used as beam guides, radio-frequency cavities, microwave generators
(magnetrons/klystrons), and field-emission electron beam diodes.
Installation: A radiation source, with its associated equipment, and the space in which it is located.
Installation enclosure: The portion of an X-ray installation that clearly defines the transition from a
noncontrolled to a controlled area and provides such shielding as may be required to limit the dose rate in
the noncontrolled area during normal operations.
Intentional X-ray device: A device in which electrons undergo acceleration in a vacuum and collide with
a metal anode target designed to produce X-rays for a particular application. Examples include diagnostic
medical/dental X-ray devices, electron LINACs used in radiation therapy applications, portable and fixed
flash X-ray systems, X-ray diffraction and fluorescence analysis equipment, cabinet X-ray systems, some
Van de Graaff generators, and electron LINACs.
Interlock: A device for precluding access to an area of radiation hazard either by preventing entry or by
automatically removing the hazard when the device is actuated.
Ion: An atom, or molecule bearing an electric charge, or an electron that is not associated with a nucleus.
Ionizing radiation: Any electromagnetic or particulate radiation capable of producing ions, directly or
indirectly, by interaction with matter, including gamma and X-rays and alpha, beta, and neutron particles.
Lead equivalent: The thickness of lead affording the same attenuation, under specific conditions, as the
shielding material in use.
Leakage radiation: Any radiation, except the useful beam, coming from the X-ray assembly or sealed
source housing.
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Medical X-ray system: An X-ray system for medical use, generally categorized as either diagnostic or
therapeutic. Diagnostic X-ray procedures are used to obtain images of body parts; therapeutic x-ray
procedures are used to manage malignancies.
Normal operation: Operation under conditions as recommended by the manufacturer of an X-ray system
or as specified by a written SOP. Recommended shielding and interlocks shall be in place and operable.
Occupancy factor: The factor by which the workload should be multiplied to correct for the degree or
type of occupancy of the area specified.
Open-beam system: An analytical X-ray system in which one or more X-ray paths (primary as well as
secondary) are not fully enclosed.
Open installation: An industrial X-ray installation that, because of operational requirements or temporary
needs, cannot be provided with the inherent degree of protection specified for other classes of industrial
installations. Generally mobile or portable equipment where fixed shielding cannot be effectively used.
Port: In this context, an opening on the outside surface of the cabinet that is designed to remain open
during X-ray production for the purpose of moving material to be irradiated into and out of the cabinet, or
for partial insertion of an object that will not fit inside the cabinet.
Primary beam: The X-radiation emitted directly from the target and passing through the window of the X-
ray tube.
Primary radiation: Radiation coming directly from the target of the X-ray tube or from the sealed source.
Quality factor: An energy-dependent dimensionless factor by which absorbed dose is to be multiplied to
obtain, on a common scale for all ionizing radiations, the magnitude of radiation effects likely to be incurred
by exposed persons. The quality factor for X-rays, gamma rays, and most beta particles is 1.0.
Rad (radiation absorbed dose): The unit of absorbed dose. One rad equals 100 ergs per gram.
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Radiation Area: Any area accessible to individuals in which radiation levels could result in an individual
receiving a deep dose equivalent in excess of 0.005 rem (0.05 millisievert) in 1 hour at 30 centimeters from
the source or from any surface that the radiation penetrates. (10 CFR 835.2(a)).
Radiation source: A device or a material that is capable of emitting ionizing radiation.
Radiological worker: A general employee whose job assignment involves operation of radiation-
producing devices or working with radioactive materials, or who is likely to be routinely occupationally
exposed above 0.1 rem per year total effective dose equivalent. (10 CFR 835.2(a))
Radiological control technician (RCT): Any person who is actively engaged in or who has completed
facility-specific RCT training and qualification programs.
Rem (roentgen equivalent man): The unit of dose equivalence used for humans, which considers the
biological effects of different types of radiation. The dose equivalent in rem is numerically equal to the
absorbed dose in rad multiplied by the applicable quality factor.
Roentgen (R): The unit of exposure. One roentgen equals 2.58 x 10-4 coulomb per kilogram of air.
Scattered radiation: Radiation that has been deviated in direction as a result of interaction with matter and
has usually been reduced in energy.
Secondary radiation: Radiation (electrons, X-rays, gamma rays, or neutrons) produced by the interaction
of primary radiation with matter.
Shielding: Attenuating material used to reduce the transmission of radiation. The two general types of
shielding are primary and secondary. Primary shielding is material sufficient to attenuate the useful beam to
the required level. Secondary shielding is material sufficient to attenuate stray radiation to the required
level.
Shielded installation: An industrial X-ray installation in which the source of radiation and all objects
exposed to that source are within a permanent enclosure.
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Skyshine: Radiation emerging from a shielded enclosure which then scatters off air molecules to increase
radiation levels at some distance from the outside of the shield.
Stem radiation: X-rays given off from parts of the anode other than the target, particularly from the target
support.
Stray radiation: Radiation other than the useful beam. It includes leakage and scattered radiation.
Survey: An evaluation of the radiological conditions and potential hazards incident to the production, use,
transfer, release, disposal, or presence of radioactive material or other sources of radiation. When
appropriate, such an evaluation includes a physical survey of the location of radioactive material and
measurements or calculations of levels of radiation, or concentrations or quantities of radioactive material
present. (10 CFR 835.2(a)).
System barrier: The portion of an X-ray installation that clearly defines the transition from a Controlled
Area to a Radiation Area and provides such shielding as may be required to limit the dose rate in the
Controlled Area during normal operation.
Tenth-value layer (TVL): The thickness of a specified substance that, when introduced into a beam of
radiation, reduces the dose rate to one-tenth of the original value. One TVL is equivalent to 3.3 HVLs.
Unattended installation: An industrial installation that consists of equipment designed and manufactured
for a specific purpose and that does not require personnel in attendance for its operation.
Units: In accordance with 10 CFR 835.4, for all radiological units, the quantities used for records required
by 10 CFR 835 shall be the curie (Ci), rad or rem. SI units, Becquerel (Bq), gray (Gy), and sievert (Sv)
may be included parenthetically for reference to scientific standards, but are not authorized for required
records. To convert conventional radiation units to SI units, the following factors are used:
1 rad = 0.01 gray (Gy)
1 rem = 0.01 sievert (Sv)
1 Ci = 3.7 X 1010 Bq
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Use factor: The fraction of the workload during which the useful beam is pointed in the direction under
consideration.
Useful beam: The part of the primary and secondary radiation that passes through the aperture, cone, or
other device used for collimation.
Very High Radiation Area: Any area accessible to individuals in which radiation levels could result in an
individual receiving an absorbed dose in excess of 500 rads (5 grays) in 1 hour at 1 meter from a radiation
source or from any surface that the radiation penetrates (10 CFR 835.2(a)).
Warning label: A label affixed to the X-ray device that provides precautions and special conditions of use.
Workload: A measure, in suitable units, of the amount of use of radiation equipment. For the purpose of
this standard, the workload is expressed in milliampere-minutes per week for X-ray sources and in
roentgens per week at 1 meter from the source for gamma-ray sources and high-energy equipment (such as
linear accelerators, betatrons, etc.).
X-ray accessory apparatus: Any portion of an X-ray installation that is external to the radiation source
housing and into which an X-ray beam is directed for making X-ray measurements or for other uses.
X-Ray Device Control Office: A team that establishes X-ray device program requirements and standards,
provides X-ray device radiation protection consultation, and serves as the central point of contact for the
management/control of X-ray devices. This function may have a facility-specific name.
X-ray device custodian: A person designated by line management as responsible for specific X-ray
devices. This individual is responsible for designating the operators of specific X-ray devices, arranging for
the operators to attend X-ray safety training, assisting in the development and maintenance of the X-ray
device SOP, familiarizing operators with the X-ray device SOP, maintaining records of operator training
and safety interlock checks, serving as the point of contact for the line organization's X-ray devices, and
coordinating surveys with the X-Ray Device Control Office. An X-ray device custodian may also be an
X-ray device operator.
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X-ray device operator: An individual designated in writing by the X-ray-device custodian and qualified
by training and experience to operate a specific X-ray device.
X-ray diffraction: The scattering of X-rays by matter with accompanying variation in intensity in different
directions due to interference effects.
X-ray installation: One or more X-ray systems, the surrounding room or controlled area, and the
installation enclosure.
X-ray power supply: The portion of an X-ray device that generates the accelerating voltage and current
for the X-ray tube.
X-ray source housing: An enclosure directly surrounding an X-ray tube that provides attenuation of the
radiation emitted by the X-ray tube. The X-ray source housing typically has an aperture through which the
useful beam is transmitted.
X-ray system: An assemblage of components for the controlled generation of X-rays.
X-ray tube: An electron tube that is designed for the conversion of electrical energy to X-ray energy.
X-ray tube assembly: An array of components typically including the cathode, anode, X-ray target, and
electron-accelerating components within a vacuum.
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CONCLUDING MATERIAL
Review Activity: Preparing Activity:
DOE Operations Offices Field Offices DOE-EH-52
DP AL RFFO
EH CH OH Project Number:
EM ID GFO 6910-0057
NE NV
NN OR
ER RL
OAK
SR
National Laboratories Area Offices
BNL Amarillo Area Office
LLNL Ashtabula Area Office
LANL Carlsbad Area Office
PNNL Columbus Area Office
Sandia Fernald Area Office
FNL Los Alamos Area Office
West Valley Area Office
Kirtland Area Office
Pinellas Area Office
Kansas City Area Office
Miamisburg Area Office
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